The UN Security Council has unanimously approved a resolution demanding a 30-day ceasefire in Syria.
The 15-member council voted to allow aid deliveries and medical evacuations.
It follows a week of intense bombardment of the Eastern Ghouta rebel enclave, near Damascus, by government forces. But after the vote, activists said air strikes were continuing.
The vote had been delayed several times since Thursday as members struggled to come to an agreement.
Russia, an ally of Syria’s government, wanted changes. Western diplomats accused Moscow of stalling for time.
The US ambassador to the UN, Nikki Haley, called for the ceasefire to be implemented immediately, but said she was sceptical that Syria would comply.
Russia’s UN envoy, Vassily Nebenzia, said the ceasefire would not be possible without agreements between warring factions.
The Syrian Observatory for Human Rights, a UK-based monitoring group, said warplanes struck the Eastern Ghouta minutes after the council adopted the resolution late on Saturday.
Earlier the observatory said 500 people had been killed in the enclave since last Sunday.
UN Secretary General Antonio Guterres has said the situation in the Eastern Ghouta was like “hell on Earth”.
Why was there a delay?
The draft said the ceasefire would not apply to operations against the Islamic State group, and the Nusra Front – a former al-Qaeda affiliate in Syria.
Russia wanted it to go further to include other groups “co-operating with them”.
The final text specified that operations could continue against “individuals, groups, undertakings and entities” associated with the terror groups, according to AFP news agency.
Ms Haley blamed Russia for having “dragged out the negotiations”. She said: “In the three days it took us to adopt this resolution, how many mothers lost their kids to the bombing and the shelling?”
France’s UN representative also said the action was very “belated”. On Friday he said failure to act could spell the end of the UN itself.
How bad is the situation in the Eastern Ghouta?
On Saturday, the Syrian Observatory said at least 29 civilians were killed, including 17 in the main town, Douma – bringing the total to over 500 for the week.
The group said the strikes were being carried out by both Syrian and Russian planes – although Russia denies direct involvement.
Barrel bombs and shell fire have been dropped on the area, where some 393,000 people remain trapped.
Aid groups report several hospitals being put out of action since Sunday.
The Syrian government has denied targeting civilians and said it is trying to liberate the Eastern Ghouta from “terrorists” – a term it has used to describe both the jihadist militants and the mainstream rebel groups that hold the enclave.
Who are the rebels?
The rebels in Eastern Ghouta are not one cohesive group. They encompass multiple factions, including jihadists, and in-fighting between them has led to past loses of ground to the Syrian government.
The two biggest groups in the area are Jaish al-Islam and its rival Faylaq al-Rahman.
The latter has in the past fought alongside the jihadist group Hayat Tahrir al-Sham – an alliance of factions led by the Nusra Front, which sprung from al-Qaeda.
The Syrian government is desperate to regain the territory, because it says the rebels are directly endangering the capital.
Eastern Ghouta is so close that it is possible for rebels to fire mortars into the heart of Damascus, which has also led to civilian deaths.
Syrian state media said rebels have killed at least 16 civilians in eastern districts of the city since Sunday.