An airstrike has hit a maternity hospital in northern Syria supported by Save the Children, the charity has said.

Two people were killed in the attack, and several others injured including a woman who was six months pregnant who lost her leg. Several babies were also hurt when their incubators crashed to the floor in the attack.

The hospital was the only one providing maternity services in the area and delivered about 300 babies a month.

The strike on the hospital in Kafar Takharim in a rebel-held part of north-western Idlib province came after earlier airstrikes that killed at least five people and injured more than 25, the Syrian Observatory for Human Rights said.

The organisation said the airstrike, which also hit a civil defence unit, had left the hospital so badly damaged it was barely operational. The nearest working maternity unit is now about 70 miles away, according to Reuters.

Sonia Khush, Save the Children’s Syria director, described the bombing as a “shameful act, whether it was done intentionally or because due care was not taken to avoid civilian areas”.

She added: “There is no excuse, and unfortunately this is only the latest in a series of strikes on health facilities in Syria. We condemn these attacks, which are illegal under international law, in the strongest possible terms. We need an immediate ceasefire across Syria and an end to the appalling bombing of medical facilities.”

Save the Children shared a video on Twitter of wreckage on a street which it said showed the aftermath.

The charity had already warned that the battle for nearby Aleppo was taking an unacceptable toll on children, who make up a third of all casualties there, according to a partner organisation still operating in the city.

Russian and government forces completely cut off access to the city this week. They have urged civilians to leave through humanitarian corridors, but there is widespread distrust among those clinging to life in the city who fear the offer of safe passage could be a ruse.

There were no reports of civilians using the corridors on Friday. “I haven’t seen any family or people trying to cross,” said Khaled Khatib, a volunteer for the Civil Defense search-and-rescue brigade, who warned anyone leaving risked being shot by snipers or detained for suspected opposition sympathies.

The UN envoy for Syria has urged Moscow to leave the creation of any humanitarian corridors to the United Nations and its partners. Aid groups have said that the children under siege are in need of urgent support.

“The situation for an estimated 100,000 children trapped under siege and bombardment in Aleppo is desperate and needs our urgent help,” said Sonia Khush, Save the Children’s Syria director.

“The world cannot turn its back while children are bombed and then denied medical treatment – we need an end to the indiscriminate attacks on civilians and immediate and unfettered access for humanitarian aid.”

Overall health conditions in besieged parts of Aleppo are grim. The death rate is rising because a government blockade of rebel-held areas means the most critical patients can no longer be evacuated to Turkey, according to the NGO Shafak, which runs a network of ambulances.

The siege has so effectively starved the group of fuel supplies that they can only respond to major airstrikes now, and heavy bombardment means limb amputations and head trauma are now the most common injuries they see.

“Life in Aleppo city is becoming more like living next to an active volcano,” said Rami, whose name has been changed to protect his identity. “You don’t know when you’ll be killed. It’s the first time in the last four years where we see this kind of bombardment and destruction.”