BEIRUT -- Airstrikes pounded rebel-held eastern Aleppo on Thursday, killing more than 20 people and hitting a water pumping station on the third day of a renewed air campaign on the besieged territory, Syrian activists and rescue workers said.

The Russian military meanwhile said airstrikes in the rebel-held province of Idlib earlier this week killed at least 30 members of an al Qaeda-linked group, including three commanders. The strikes are part of a major Syrian and Russian offensive launched earlier this week on opposition-held areas that has killed dozens of people.

In one area, volunteer first responders dug through the rubble for four hours before pulling out a 6-year-old child who was still alive. The child’s mother was killed in the strikes, said Ibrahim al-Haj, a spokesman for the rescuers, known as the Syrian Civil Defense.

The activist-run Public Services Authority said the Bab al-Nairab water plant was struck with a barrel bomb. Spokesman Ahmad al-Shami said the plant was damaged but is still operating.

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“This regime uses any means to add pressure to civilians. It has bombed bakeries and hospitals and has not made an exception for water and electricity,” he told The Associated Press.

Airstrikes on Wednesday struck the city’s central blood bank and a children’s hospital. Medical facilities have repeatedly come under attack during the Syrian conflict, with 126 such incidents this year alone, according to the World Health Organization.

Doctors Without Borders said the children’s hospital and a specialized surgical hospital were hit by Wednesday’s strikes.

“Hospital staff managed to move children - including prematurely born babies - from cots and incubators to the basement of the building in order to shelter them from the bombing,” said the aid group, which sponsors both hospitals.

The Oxfam aid group said the more than 250,000 residents of eastern Aleppo have limited food and clean water as winter approaches, and are at risk of disease outbreaks.

No U.N. aid has reached eastern Aleppo since July, and the U.N. has warned that supplies will run out this week. Oxfam said it helped move a generator to the besieged area on Wednesday to improve the water supply.

“Clean water is vital, but it won’t stop starvation, never mind protect people from indiscriminate aerial attacks,” said Andy Baker, who is leading Oxfam’s Syria response.

The Syrian Civil Defense said 28 people were killed in and around Aleppo on Thursday. The Britain-based Syrian Observatory for Human Rights, which relies on a network of local activists, put the death toll at 25.

At least 70 people were killed in northern Syria on Tuesday and Wednesday.

Russia says it is not bombing Aleppo as part of the offensive announced this week, but is instead targeting insurgents in Idlib and the central Homs province.

Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said the strikes targeting al Qaeda took place in Idlib on Tuesday, and were launched from Russia’s only aircraft carrier, the Admiral Kuznetsov, which recently deployed to the Mediterranean Sea.

He said three leading members of the al Qaeda-linked Fatah al-Sham Front - Muhammad Helala, Abu Jaber Harmuja and Abul Baha al-Asfari - were among those killed. He said al-Asfari had overseen the group’s attempts to break the siege of Aleppo.

Al-Asfari had led a moderate rebel group in 2013, and it was not clear if or when he joined the al Qaeda-linked group.

An opposition media group known as All4Syria reported that the two other named militants were killed Tuesday in an airstrike in the village of Kfar Jalis, in the Idlib countryside, that also killed six civilians. The Observatory’s chief Rami Abdurrahman said the airstrike on the jihadi stronghold killed six leading militants, without identifying them.

The same village was struck Thursday, the Observatory said, killing six civilians from the same family.

The Russian Defense Ministry said long-range bombers dispatched from Russia fired cruise missiles at Islamic State of Iraq and Syria, or ISIS, and al Qaeda targets in Syria during a 7,000-mile flight. It said fighter jets from the carrier and an air base in Syria also took part in the strikes. It did not say where the strikes took place, but said they destroyed command facilities, ammunition depots and weapons factories.

Months of negotiations between the U.S. and Russia failed to cement a long-term cease-fire in Aleppo, which has become the focus of the war between Syrian President Bashar Assad and rebels fighting to topple him.

Al Qaeda’s Syrian affiliate is fighting alongside the rebels, but ISIS has no presence in Aleppo.