Intensive bombings pummeled Syria's rebel-held eastern neighborhoods of the city of Aleppo on Friday, residents and rescuers said, hitting an area housing several hospitals and sending the chief of a pediatrics clinic in a frantic search for a place to move his young patients.

Earlier Friday, airstrikes on a village in the rural Aleppo province killed seven members of the same family, including four children, opposition activists said.

The attacks mark the fourth day of renewed assault by Syrian government warplanes on eastern Aleppo districts, a rebel-held enclave of 275,000 people. The onslaught began with a Russian announcement of its own offensive on the northern rebel-controlled Idlib province and the central Homs province.

So far, more than 100 people have been killed across northern Syria since Tuesday.

A physician who identified himself as Dr. Hatem, the head of the only pediatric hospital remaining in besieged rebel-held part of Aleppo, said his facility in the al-Shaar neighborhood has been targeted once more on Friday, causing damages to its exterior. The hospital was also hit during a wave of airstrikes on the complex housing four hospitals on Wednesday.

"Now it is being bombed ... I am sorry ... I have to go to transfer the children" to a safe area, he said in a text message. He uses his first name fearing for his family's safety.

Another Aleppo hospital in a different neighborhood across town also was bombed late on Thursday, he said. The entrance was set on fire but no one was wounded.

The Britain-based Syrian Observatory for Human Rights said that dozens of airstrikes, artillery and barrel bombs hit 18 different neighborhoods in eastern Aleppo.

The Observatory said government bombings have targeted areas housing hospitals, including one with the children's hospital and another nearby with one of the few remaining intensive care units in eastern Aleppo.

Many hospitals and clinics in the besieged area have moved their operations underground after months of relentless bombings and airstrikes. The World Health Organization said in 2016, it recorded 126 attacks on health facilities, a common tactic in the war in Syria.

Russia and the Syrian government deny targeting hospitals in airstrikes.

The city of Aleppo, once Syria's commercial hub, has been divided since 2012, with the eastern half in rebel hands and the western half controlled by government forces.

Ibrahim al-Haj, a member of the Syria Civil Defense rescuers in Aleppo said the city "is a mess." The group of rescuers and first responders said they were struggling to put out fires set off by the bombings in at least 10 different areas of eastern Aleppo.

The Observatory said at least three people were killed in the attacks on the city's districts.

The Observatory also said the strike that killed the seven from one family took place in southwestern Aleppo. Syrian Civil Defense posted photographs online showing children's bodies covered with dust and blood.