BEIRUT -- A new wave of airstrikes and shelling on eastern suburbs of the Syrian capital Damascus left more than 20 people dead and dozens wounded Saturday, raising the death toll during a week of bombing in the area that has killed scores of women and children. The Britain-based Syrian Observatory for Human Rights said airstrikes that hit several suburbs left 22 people dead in different areas, including 10 in the suburb of Douma.

The opposition's Syrian Civil Defense, also known as the White Helmets, said 23 people were killed.

The Observatory said that since the latest wave of bombardment began Sunday, 510 civilians, including 127 children and 75 women, have been killed in eastern Ghouta. The White Helmets said it has documented the names of 420 people who have been killed since Sunday, adding that dozens more have still not been identified.

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The weeklong bombardment has overwhelmed rescuers and doctors at makeshift hospitals, many of which have also been bombed. Activists say that terrified residents have been hiding in underground shelters where dozens of people can be crammed into small places.

Washington Post Middle East reporter Louisa Loveluck, speaking on CBSN, said Ghouta is a place where civilians don't have an outside power to turn to.

"The stories we've heard from residents this week are among the worst we've heard during the entire war. Medics are totally overwhelmed, they're working around the clock with hundreds of casualties strewn through their doors, and in fact, the area is so under-equipped that doctors are left in a position to choose who lives and who dies because they don't have the resources to treat everyone," Loveluck said.

The latest wave of bombings came after the U.N. Security Council delayed a vote Friday on a resolution demanding a 30-day humanitarian cease-fire across Syria in hopes of closing a gap over the timing for a halt to fighting. A vote was scheduled for Saturday.

People walk through the damage, after an air raid in the besieged town of Douma, Eastern Ghouta, Damascus, Syria February 23, 2018. Bassam Khabieh / REUTERS

Russia's U.N. Ambassador Vassily Nebenzia has called an immediate cease-fire unrealistic, and in an apparent bid to get Russian support, sponsors Kuwait and Sweden amended the draft resolution to drop a demand that the cease-fire take effect 72 hours after the resolution's adoption.

Instead, the new text circulated Friday night "demands that all parties cease hostilities without delay." The latest draft resolution says a cease-fire must be followed immediately by access for humanitarian convoys and medical teams to evacuate the critically ill and wounded.

Russia has been a main backer of Syrian President Bashar Assad since the country's conflict began seven years ago. In 2015, Moscow joined the war on Assad's side tipping the balance of power in his favor.

Syrian opposition activists say Russian warplanes are taking part in bombarding Damascus' eastern suburbs, also known as eastern Ghouta, where many people are hiding in underground shelters with little food and medical supplies amid a tight government siege.

Syrian opposition activists said that government forces used phosphorous bombs in their attacks on the suburbs, but the claims could not be independently confirmed.

Syrian state media reported that rebels fired mortar shells on Damascus, Assad's seat of power, killing at least one person and wounding seven.