BEIRUT — Doctors in Syria’s rebel-controlled suburbs of Damascus said Wednesday they were unable to keep up with the staggering number of casualties, amid a ferocious bombing campaign by government forces that has targeted hospitals, apartment blocks and other civilian sites, killing and wounding hundreds of people in recent days.

The bombardment has forced many among the nearly 400,000 residents to sleep in basements and makeshift shelters, and has overwhelmed rescue workers who have spent days digging out survivors from the wreckage of bombed out buildings.

Dr. Waleed Awata described a desperate, chaotic scene at the small hospital where he works as an anesthesiologist in the town of Zamalka, one of a cluster of settlements that make up the Damascus suburbs known as eastern Ghouta. The facility, with just 17 beds, received 82 patients on Tuesday night alone, he said.

“We had to give them IVs and treat them on the floor,” the 44-year-old physician told The Associated Press. He said the bodies of two women and two children killed in Wednesday’s shelling were also brought to the hospital.

The hospital was struck Tuesday by barrel bombs – crude, explosives-filled oil drums dropped from helicopters at high altitudes – as well as sporadic artillery fire, Awata said. Like many hospitals in the area, patients had been moved into the basement to shield them from airstrikes. No one was hurt but the hospital’s generator, water tanks and several ambulances were damaged.

Another doctor said he, too, was as the hospital where he works in the town of Saqba when it came under attack Tuesday, killing some of the patients and forcing others to be moved to nearby homes because the airstrikes made it too dangerous to take them to other hospitals.

“By God, I am exhausted in every sense of the word,” said the physician, who spoke on condition of anonymity because he feared for the safety of relatives in government-controlled areas of Damascus.

The international medical organization Doctors Without Borders said 13 hospitals and clinics that it supports have been damaged or destroyed over the past three days. The International Committee of the Red Cross called for immediate access to tend to the wounded, saying medical personnel in the rebel-held areas were unable to cope amid shortages of medicines and supplies.

Syrian government forces supported by Russian aircraft have shown no signs of letting up their aerial and artillery assault on eastern Ghouta since they stepped up strikes late Sunday as part of a new, determined push to recapture the territory that has been controlled by rebels since 2012.

The U.N. human rights office said in a statement Wednesday that at least 346 people had been killed in eastern Ghouta since the Syrian government and its allies escalated their offensive on the region on Feb. 4. At least 92 of those deaths occurred in just one 13-hour period on Monday, it said, adding that the toll was far from comprehensive, documented in the midst of chaos and destruction. Another 878 people have been wounded, mostly in airstrikes hitting residential areas.

The Britain-based Syrian Observatory for Human Rights, which closely monitors the fighting through activists on the ground, said at least 300 people have been killed since Sunday night alone. The dead included 10 people killed in a new wave of strikes Wednesday on the town of Kafr Batna.

The opposition’s Syrian Civil Defense search-and-rescue group, also known as the White Helmets, reported similar numbers, saying government forces targeted the town with airstrikes, artillery fire and barrel bombs. Photos and video posted by the Syrian Civil Defense and local activist groups showed scenes resembling an earthquake.