BEIRUT (Reuters) - Dozens of air strikes hit rebel-held areas of the northern Syrian city of Aleppo overnight, a monitor and defense worker said, continuing a fierce air campaign by Syrian government and allied forces since a ceasefire broke down almost a week ago.

A man walks on the rubble of damaged buildings after an airstrike on the rebel held al-Qaterji neighbourhood of Aleppo, Syria September 25, 2016. REUTERS/Abdalrhman Ismail

The Syrian Observatory for Human Rights said dozens of air strikes hit the rebel-held half of the divided city, the target of a fresh offensive announced by the Syrian army on Thursday.

Aleppo has become the main battle ground of a conflict now in its sixth year. Capturing rebel districts of Syria’s largest city, where more than 250,000 civilians are trapped, would mark the biggest victory of the civil war for Syrian President Bashar al-Assad’s forces.

Bebars Mishal, a civil defense worker in rebel-held Aleppo, said the bombardment continued until 6 a.m. (0300 GMT).

“It’s the same situation. Especially at night, the bombardment intensifies, it becomes more violent, using all kinds of weapons, phosphorous and napalm and cluster bombs,” Mishal told Reuters.

“Now, there’s just the helicopter, and God only knows where it will bomb. God knows which building will collapse,” he said.

Another civil defense worker, Ismail al-Abdullah, said the overnight bombardment had been less intense than it had been in the past few days and the morning was relatively quiet.

The Observatory said it had documented the deaths of 237 people, including 38 children, from air strikes on Aleppo city and the surrounding countryside since last Monday when the ceasefire ended. Of those documented deaths, 162 were in rebel-held east Aleppo city.

Civil defense workers say about 400 people have died in the past week in the rebel-held parts of the city and surrounding countryside.

Rescue efforts have been severely hampered because bomb damage has made roads impassable and because civil defense centers and rescue equipment have been destroyed in raids.

Civil defense worker Ammar al Selmo said rescuers have only two fire trucks and three ambulances left in Aleppo and that three fire trucks, two ambulances and three vans had been hit in the past week.

“We are trying to respond ... but we don’t know what tomorrow will bring,” Selmo said, speaking from Gaziantep, Turkey after recently leaving east Aleppo.

Brita Hagi Hassan, president of the city council for opposition-held Aleppo, said the bombardment over the past three days has been exceptional.

“The planes are not leaving the skies at all ... Life in the city is paralyzed. Everyone is cooped up in their homes, sitting in the basements. These missiles are even targeting the basements and shelters that we’d set up to protect people,” he said from the Aleppo countryside. Hassan has been unable to get back into east Aleppo for several weeks because of the siege.

On Saturday a pumping station providing water for rebel-held eastern Aleppo was destroyed by bombing.

“People are now relying on water from the wells, and that water is not suitable for drinking. It was being used for other things, like washing, cleaning and so on. Now, the people are relying on it as drinking water,” Hassan said.

Selmo said eight people died on Monday in air strikes on east Aleppo and the surrounding countryside.

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Hundreds of thousands of people have been killed in Syria’s civil war and 11 million driven from their homes.

“I don’t know what’s going to happen in the future. But it looks like there’s more killing, more bombardment, more blood on the horizon,” Hassan said.

In Homs, a second group of Syrian rebels began to be evacuated from their last foothold in the city on Monday, state news agency SANA said.

The Observatory said around 100 fighters were in the group scheduled to leave to the northern Homs countryside.

The first batch of around 120 fighters and their families left on Thursday. The evacuations are part of the Syrian government’s attempts to conclude local agreements with rebels in besieged areas that have resulted in rebels being given safe passage to insurgent-controlled areas.