The UN Security Council has unanimously approved a resolution demanding a 30-day ceasefire across Syria "without delay" to deliver humanitarian aid to millions and evacuate the critically ill and wounded.
The sponsors, Kuwait and Sweden, amended the resolution late on Friday in a last-minute attempt to get Russian support, dropping a demand that the ceasefire take effect in 72 hours.
Russia's UN Ambassador Vassily Nebenzia had said repeatedly that an immediate ceasefire was unrealistic.
Sweden's UN Ambassador Olof Skoog said before the vote that the resolution could de-escalate violence and save lives.
"The UN convoys and evacuation teams are ready to go," he said.
Earlier: Air strikes on Damascus suburbs claim more lives
A new wave of air strikes and shelling on eastern suburbs of the Syrian capital Damascus has left at least 22 people dead and dozens wounded.
The weeklong bombardment has killed 500 people, including scores of women and children.
It 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.
The latest wave of bombings came after the UN Security Council delayed a vote on a resolution demanding a 30-day humanitarian ceasefire across Syria in hopes of closing a gap over the timing for a halt to fighting.
A vote was scheduled for later on Saturday.
Russia's UN Ambassador Vassily Nebenzia has called an immediate ceasefire unrealistic, and in an apparent bid to get Russian support, sponsors Kuwait and Sweden amended the draft resolution to drop a demand that the ceasefire take effect 72 hours after the resolution's adoption.
Instead, the new text circulated on Friday night "demands that all parties cease hostilities without delay".
The latest draft resolution says a ceasefire 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 Mr Assad's side tipping the balance of power in his favour.
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.
The Britain-based Syrian Observatory for Human Rights said air strikes that hit several suburbs left 22 people dead in different areas, including 10 in the suburb of Douma.
The opposition's Syrian Civil Defence, also known as the White Helmets, said 23 people were killed.
The Observatory said that since the latest wave of bombardment began on 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.
Syrian state media reported that rebels fired mortar shells on Damascus, Mr Assad's seat of power, killing at least one person and wounding seven.