A fourth consecutive day of heavy regime raids on the rebel-held enclave of Eastern Ghouta near the capital Damascus killed 22 civilians on Thursday, the Syrian Observatory for Human Rights said as exhausted emergency workers struggled to rescue and treat affected residents. The civilian toll was first reported at nine on Thursday morning but almost immediately began to rise, mirroring previous bloody days in the besieged district.  Wednesdays strikes hit at least six different locations in Eastern Ghouta, said the head of the Britain-based Observatory, Rami Abdel Rahman.  The highest toll was in the town of Jisreen, where eight civilians were killed.  An estimated 400,000 people live in Eastern Ghouta under a suffocating regime-imposed siege, which has made food and medicine nearly impossible to access. Syrian regime warplanes have ratcheted up their bombardment of Eastern Ghouta this week, leaving dozens dead and hundreds in need of medical care.  In apparent retaliation, one person was killed in rebel mortar fire on the regime-controlled part of the town of Harasta, according to state news agency SANA.  The uptick in bombardment on Eastern Ghouta has left already-overburdened medical staff and emergency workers struggling to rescue and treat affected residents. "We cant keep up. Were trying as much as we can," rescue worker Abu Mohammad Omar told AFP. "Were rushing, doing the work that were doing, but we cant get to everything." With few bulldozers and precious little fuel to operate them, rescue workers are struggling to reach trapped civilians in time, said Omar. The 23-year-olds voice cracked as he described trying to find survivors in the rubble of a five-storey building in the town of Douma on Tuesday. "There was a huge, huge escalation against the city. More than one place was reduced to rubble. The machines we had couldnt keep up," he said. They searched one collapsed building for 10 hours for any survivors, but eventually had to move on to another bomb site.  At 1:00 am on Wednesday morning, after scouring the rubble for a single suspected survivor, a salvo of bullets and rockets forced them to abandon the search. Abu Samer, an ambulance driver in the town of Hammuriyeh, said he sometimes jumps into his vehicle to find the petrol tank empty.  "The difficulty for us is the lack of fuel. If there was fuel, I could go to any bomb site," the 40-year-old told AFP. The city streets on Wednesday were a hellish scene, Abu Samer said: no signs of life, but piled high with rubble and human remains. Doctors are also struggling at Eastern Ghoutas stretched hospitals. "Every day, they bring us a lot of wounded people. Sometimes we can keep up, other times we cant," said Osama, a paramedic at the Damascus Countryside Specialised Hospital.