The gaps between explosions scarcely stretch five seconds at their longest.
Blast after blast rumbles around the landscape and above the low cloud, fighter jets roar overhead.
The sound of Israeli artillery firing from farmland east of Gaza is answered seconds later by the sound of impacts inside the Strip.
When the rumble of an explosion subsides, the brief period of calm is sometimes quiet enough to make the chatter of machine gun fire audible.
Glimpsed through haze from a hill on the outskirts of the border town of Sderot, the buildings of Beit Hanoun in the northern Gaza Strip are smudged with smoke and often broken and crumbled from blasts.
The day after Israel announced it was expanding ground operations in the besieged coastal enclave, the din proved the assault was clearly still ongoing.
It was also clear that the scale of the assault was larger and the duration longer than any of the brief cross-border tank raids that Israel has conducted so far.
The Israel Defense Forces (IDF) released videos showing heavy strikes inside Gaza and armoured vehicles moving through the territory.
Heavily armoured bulldozers were seen clearing paths and columns of armour driving along roads in what looked like the edge of the Strip.
Targeting footage also showed several strikes on buildings in the enclave.
The IDF said it had struck terror cells preparing missile and mortar attacks and directed a combat helicopter to strike an apartment housed by Hamas operatives.
Israel said that “combined combat forces of armour, combat engineers and infantry have been operating on the ground in the northern Gaza Strip”.
“As part of the operation, IDF soldiers identified terrorist cells attempting to launch anti-tank missiles and mortar shells and struck them.”
Witnesses inside the 25-mile-long Hamas-controlled Strip where some 2.3 million people are trapped said the bombardment that preceeded Israel’s push was the largest yet to hit the territory in the war.
As communications collapsed amid the onslaught, ambulances were left blindly driving towards explosions as they scrambled to treat the wounded.
By midday after the declaration of the push, Rear Adml Daniel Hagari, the spokesman for the IDF, said its forces “are still on the ground and are continuing the war”.
He said the military was “advancing through the stages of the war” in Gaza.
“Infantry, armoured, engineering and artillery forces participating in the activity, accompanied by heavy [air] fire,” he said.
The IDF on Friday night announced what it called an expansion of ground operations as a spokesperson for Benjamin Netanyahu, Israel’s Prime Minister, vowed that “Hamas will feel our anger tonight”.
At the same time, the large force of armour, artillery and reservists that Israel has deployed around the Gaza Strip since the Oct 7 attacks began what was clearly its biggest operation to date.
Mr Netanyahu launched the escalated assault after weeks of internal deliberation in his war cabinet, which was divided on the merits of a ground assault. He reportedly gave the green light after hostage negotiations ended in stalemate.
Hamas leaders quickly said they were facing at least two armoured thrusts into the territory: one at Beit Hanoun in the northeast corner, and another halfway down the eastern side at Bureij. There were also reports of clashes between the IDF and Hamas in the northern town of Beit Lahia.
“Al-Qassam Brigades and all Palestinian resistance forces are fully prepared to confront the aggression with full force and thwart the incursions,” the terror group said.
These appeared heavier and more long-lived than night-time incursions conducted earlier in the week, which were described as raids to prepare the ground for an invasion.
Footage released by the IDF showed columns of Israeli tanks and armoured vehicles operating inside the Strip.
It was still unclear if Friday night’s assault marked the beginning of a long-awaited ground offensive, or an increase in the tempo and weight of smaller probing attacks.
Israeli leaders have been divided on whether to launch an all-out assault, a more incremental offensive, or a series of smaller, more targeted clearing operations.
IDF commanders gave little information about how the incursion was proceeding and a complete collapse of communications inside the enclave left trapped residents unable to communicate with each other or the outside world.
But, as the assault continued, Yoav Gallant, the defence minister, declared Israel had “moved to the next stage in the war”.
He said: “Last evening, the ground shook in Gaza. We attacked above ground and underground... The instructions to the forces are clear. The campaign will continue until further notice.”
The IDF also stressed the number of underground targets that were being hit, underlining the importance to Israel of taking out the tunnel system known as the “Gaza Metro”.
Its aircraft had hit 150 underground targets in the northern Gaza Strip overnight, “including terror tunnels, underground combat spaces and additional underground infrastructure,” a statement said.
Hamas has had years to prepare formidable defences in the densely populated enclave. Israel faces house-to-house fighting, narrow, booby-trapped alleyways and as many as 300 miles of tunnels.
Such urban combat was “like walking down the street waiting to get punched in the face”, John Spencer, a retired US army major and the chair of Urban Warfare Studies at the Modern War Institute at West Point, told the Associated Press.
Urban defenders, he explained, “had time to think about where they are going to be and there’s millions of hidden locations they can be in. They get to choose the time of the engagement - you can’t see them but they can see you”.
Hamas has a massive network of tunnels, some of them 230ft deep, allowing the group to transport weapons, supplies and fighters out of the sight of Israeli drones.
Yehiyeh Sinwar, Hamas’s political leader, claimed in 2021 that the militant group had more than 300 miles of tunnels.
Yocheved Lifshitz, an 85-year-old woman held hostage after the Oct 7 raids, said last week when she was released that she had been held in a “spiderweb” of tunnels, walking for several miles.
The IDF has long known that this network would be a significant obstacle to any major incursion into Gaza. Israeli commanders have built specialised teams in the IDF’s engineering corps that have been grouped into tunnel reconnaissance units, while troops regularly train in mock tunnel systems.
Yet even with such preparation, clearing the tunnels will be a claustrophobic and terrifying task, warned Daphné Richemond-Barak, a professor at Israel’s Reichman University who wrote a book on underground warfare.
She told the Associated Press: “When you enter a tunnel, it’s very narrow, and it’s dark and it’s moist, and you very quickly lose a sense of space and time.
“You have this fear of the unknown, who’s coming around the corner? Is this going to be an ambush? Nobody can come and rescue you. You can barely communicate with the outside world, with your unit.”
With communications down, desperate Palestinians in Gaza were using mosque loudspeakers to communicate with each other.
Video footage posted online overnight showed mosques broadcasting anguished emergency messages using speaker systems that usually would deliver the call to prayer.
“The communications have been cut,” stated one message broadcast over a mosque’s loudspeakers. “All help from the outside world has been cut. Oh, Allah only you are left… we are dependent on your strength over theirs.”
Israel appeared to have cut all internet access in the Gaza Strip, causing a near total information blackout that continued through Saturday morning as its troops mounted an incursion in the north.
Media organisations, including The Telegraph, have lost contact with colleagues on the ground, making it difficult to confirm what has taken place in the blockaded strip since Friday night.
Some reports have trickled through, including a dispatch from Rushdi Abualouf, a BBC Gaza correspondent, who described the situation as “total chaos”.
“There was a huge bombardment in the north of Gaza Strip on a scale we’ve never seen before,” he reported on Saturday. “Huge flames could be seen rising into the sky – it seemed they were using different types of bombs.”
Ambulance drivers have no means of coordinating due to the internet outages, he added.
“At the hospital here ambulance drivers told me they couldn’t communicate with anyone, so they were just driving in the direction of the explosions.”
“There’s been panic everywhere, even here in Khan Younis, where the bombing was less, as people try to reach family members in other areas to check they are safe, but the phones have been cut off.”
The Committee to Protect Journalists has warned the world “is losing a window into the reality” of the conflict due to the lack of internet in Gaza. It also said that the lack of information could lead to a flood of “deadly propaganda, dis- and misinformation”.
It came as the World Health Organisation said it had completely lost touch with its staff on the ground.
“The blackout is also making it impossible for ambulances to reach the injured,” Tedros Adhanom Ghebreyesus, the WHO chief, wrote in a post on Twitter.
“The evacuation of patients is not possible under such circumstances, nor to find safe shelter,” he added.
Arab Gulf states on Saturday warned Israel against further ground operations in the Gaza Strip, with Saudi Arabia denouncing land incursions as “unjustified” and Oman condemning possible “war crimes”.
Saudi Arabia “condemns and denounces any ground operations carried out by Israel due to the threat they pose to the lives of Palestinian civilians”, the kingdom’s foreign ministry said in a statement.
It cautioned against “the danger of continuing to carry out these blatant and unjustified violations of international law against the brotherly Palestinian people”, warning of “serious repercussions for the stability of the region”.
Mohammed bin Abdulrahman Al-Thani, Qatar’s foreign minister, said an “Israeli ground escalation would have dire consequences for civilians and devastating humanitarian and economic impacts”.
The United Arab Emirates on Saturday night asked the United Nations Security Council to meet “as soon as possible”.