Iraqi Federal Police inspect the bodies of ISIS fighters at Dawasa district as the battle against ISIS continues in the city of Mosul, on March 22, 2017.

Dozens of residents were buried in collapsed buildings in the Iraqi city of Mosul after an air strike against ISIS triggered a massive explosion last week and rescuers are still recovering bodies, civil defence agency officials and locals said on Thursday.

The exact cause of the collapses was not clear, but a local lawmaker and two local residents said air strikes by the US-led coalition targeting ISIS militants may have detonated a truck filled with explosives, destroying buildings in a heavily populated area.

Civil Defence chief Brigadier Mohammed Al-Jawari told local reporters that rescue teams were retrieving bodies from under the debris in the Mosul Jadida district near Rahma hospital, the site of heavy fighting between Iraqi forces and ISIS.

Reports of numbers of civilian casualties varied greatly after last Friday’s air raid. But Jawari was quoted by al-Mosuliliya channel in a statement saying teams had so far recovered 40 bodies from buildings that collapsed.

“Finding survivors is very difficult because the area is completely destroyed,” he told reporters. “It’s a very big disaster, indeed we can describe it as a disaster.”

The coalition did not give details on any specific air strike or comment on a Mosul Jadida district operation.

“We are aware of reports on airstrikes in Mosul resulting in civilian casualties. The Coalition conducted several strikes near Mosul and we will provide this information to our civilian casualty team for further investigation,” the coalition said in a statement.

One Iraq official put the total casualties at more than 137. Bodies were believed to be still buried inside collapsed homes.

“A coalition air strike hit a residential street last Friday and destroyed at least 30 houses,” a police civil defense official said. “We halted rescue operations today for lack of heavy equipment, jack hammers and trucks to remove debris.”

Local lawmaker Faris al-Sanjari told Reuters the coalition air strike had targeted a truck bomb causing a huge explosion.

“You can’t kill dozens just to destroy a booby-trapped truck parked near houses,” he said.

One witness told Reuters heavy air strikes in the area began on March 7, but on Friday a strike hit a massive ISIS truck bomb in a residential area, which exploded and destroyed seven homes where dozens of people were hiding.

Another resident said 25 homes were damaged. With fighting still going on, residents have been unable to recover bodies since the strike, the resident said.

Rights groups have expressed concern over the mounting civilian death toll, with ISIS fighting among homes and densely-populated areas as the campaign to defeat the militant group in its last Iraqi stronghold enters its sixth month.

Iraqi military and US-led coalition have been countering with heavy weaponry and air strikes to support troops on the ground moving into the narrow alleyways of Mosul’s Old City.

Families fleeing Mosul have talked of high numbers of civilians killed by air strikes, and said that in many cases ISIS fighters using homes as cover have already slipped away by the time airstrikes hit. Other displaced residents say they have been forced to act as human shields.

New push forward

About 400,000 Iraqi civilians are trapped in the ISIS-held Old City of western Mosul, short of food and basic needs as the battle between the militants and government forces rages around them, the United Nations refugee agency said on Thursday.

Many fear fleeing because of ISIS snipers and landmines. But 157,000 have reached a reception and transit center outside Mosul since the government offensive on the city’s west side began a month ago, said Bruno Geddo, the UN High Commissioner for Refugees (UNHCR) representative in Iraq.

“The worst is yet to come. Because 400,000 people trapped in the Old City in that situation of panic and penury may inevitably lead to the cork-popping somewhere, sometime, presenting us with a fresh outflow of large-scale proportions,” he said.

Fighting in the past week has focused on the Old City, with government forces reaching as close as 500 meters to the al-Nuri Mosque, from where ISIS leader Abu Bakr al-Baghdadi declared a caliphate spanning parts of Iraq and Syria in July 2014.

Around 157,000 have reached a transit center outside Mosul since the government offensive on the city’s west side began a month ago, according the UN High Commissioner for Refugees (UNHCR) officials in Iraq.