[For new developments, read about what we now know on the Wednesday after the attacks.]

The Islamic State has claimed responsibility for the coordinated attacks by suicide bombers on churches and hotels in Sri Lanka on Sunday that killed more than 350 people and wounded about 500.

The victims came from more than a dozen countries, and included worshipers at Easter services. The first mass funerals were held on Tuesday outside one of the devastated churches, in western Sri Lanka. Many of the coffins bore the remains of children.

[Grief and anger as the victims are buried.]

The authorities in Sri Lanka said the attack had been carried out by a local group, National Thowheeth Jama’ath, with help from international militants and possibly another local militant group, Jammiyathul Millathu Ibrahim.

What we know about the attacks

• Prime Minister Ranil Wickremesinghe said “foreign involvement” was likely and that some of the attackers had traveled abroad recently. “Some of the evidence,” Mr. Wickremesinghe said, pointed to links with the Islamic State, although the militant group has presented little to back up its claim of responsibility.