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.
However, 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.
US ambassador to the UN Nicky Haley called for the ceasefire to be implemented immediately, but said she was sceptical that Syria would comply.
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".