Israeli forces hit the city of Jenin with drone strikes during an overnight operation on Monday that included hundreds of troops and set off a gunbattle lasting into the day, killing at least seven people in a major escalation of West Bank violence.

With drones clearly audible overhead and the sounds of gunfire and explosives heard across the city hours after the strikes, the Jenin Brigades, a unit made up of militant groups based in the city’s crowded refugee camp, said it was engaging the Israeli forces and shot down one of the unmanned aircraft.

At times during the morning, at least six drones could be seen circling over the city and the adjoining camp, a densely packed area housing around 14,000 refugees in less than half a square kilometre.

The camp has been at the heart of an escalating spiral of violence across the West Bank that has triggered mounting alarm from Washington to the Arab world, without so far opening the way to a resumption of political negotiations that have been stalled for almost a decade.

For more than a year, army raids in cities like Jenin have become routine, while there have been a series of deadly attacks by Palestinians against Israelis and rampages by Jewish settler mobs against Palestinian villages.

“What is going on in the refugee camp is real war,” said Palestinian ambulance driver, Khaled Alahmad, describing Monday’s fighting. “There were strikes from the sky targeting the camp, every time we drive in, around five to seven ambulances and we come back full with injured people.”

The Palestinian health ministry confirmed at least seven people had been killed and 27 wounded in Jenin, while another man was killed in the city of Ramallah after being shot in the head at a checkpoint.

The Israeli military said its forces struck a building that served as a command centre for fighters from the Jenin Brigades in what it described as an extensive counterterrorism effort aimed at destroying infrastructure and disrupting militants from using the refugee camp as a base.

A spokesman said it would last as long as needed and officials suggested forces could remain for days. “An operation doesn’t end in one day,” Energy Minister Israel Katz, a member of the security cabinet, told Army radio.

Until June 21, when it carried out a strike near Jenin, the Israeli military had not used drone strikes in the West Bank since 2006. But the growing scale of the violence and the pressure on ground forces meant such tactics may continue, a military spokesman said.

“We’re really stretched,” he told journalists. “It’s because of the scale. And again, from our perception, this will minimize friction,” he said, saying the strikes were based on “precise intelligence”.

Hundreds of fighters from militant groups including Hamas, Islamic Jihad and Fatah are based in the camp, armed with an array of weapons smuggled into the West Bank or stolen from Israeli forces, and a growing arsenal of explosive devices.

Israeli forces said they seized an improvised rocket launcher and hit a weapons production and explosives storage facility.

‘Hornets nest’

Monday’s operation, involving a force described as “brigade-size” - suggesting around 1,000-2,000 troops - was intended to help “break the safe haven mindset of the camp, which has become a hornets nest,” the spokesman said.

Its apparent scale underlined the importance of the Jenin camp in violence that has further exposed the impotence of the Palestinian Authority to impose its writ over towns in the West Bank, where it holds nominal governance powers.

But it was unclear whether the incursion would trigger a wider response from Palestinian factions, drawing in militant groups in the Gaza Strip, the coastal enclave controlled by the militant Islamist group Hamas.

“The resistance will confront the enemy and defend the Palestinian people and all options are open to strike the enemy and respond to its aggression on Jenin,” said a statement from the Iranian-backed Islamic Jihad group in Gaza.

Israeli Defence Minister Yoav Gallant said his forces were “closely monitoring the conduct of our enemies.

“The defence establishment is ready for all scenarios.”

Following the last major raid in Jenin in June, Palestinian gunmen killed four Israelis near a Jewish settlement in the West Bank in an attack that led to a rampage by mobs of settlers in Palestinian villages and towns.

As daylight broke on Monday, thick black smoke from burning tyres set alight by residents swirled through the Jenin streets while calls to support the fighters rang out from loudspeakers in mosques.

A spokesman for Palestinian President Mahmoud Abbas called the operation “a new war crime against our defenceless people.”

The Israeli military, which regularly accuses militant groups of basing fighters in civilian areas, said the targeted building functioned as an “advanced observation and reconnaissance centre” and a weapons and explosives site as well as a coordination and communications hub.

It provided an aerial photograph showing what it said was the target and which indicated the building hit was near two schools and a medical centre.

Israel captured the West Bank, which the Palestinians see as the core of a future independent state, along with EastJerusalem and Gaza, in the 1967 Middle Eastern war. Following decades of conflict, peace talks that had been brokered by the United States have been frozen since 2014.