On April 11 Sri Lankan police were warned about attacks on 11 churches

The blasts at Colombo in which several people died was a clear warning to the Catholics. Although no group has claimed responsibility for the attack, the police had a week backreceived information that there would be blasts in Churches.
A message received by the police on April 11 stated that 11 Churches would be attacked. It was further warned that all the Catholics should go home and this should be informed to all the families.
With the blasts today, the intelligence in Sri Lanka has warned that there could be more attacks.
The country has been placed under very high alert and security has been tightened all over. People have been advised to stay indoors and not venture out. Investigators are on the scene and are gathering as much evidence as possible. Over 42 people were killed after six blasts ripped across several place in Colombo. Three churches - St Anthony's Church in Colombo, St Sebastian's Church in the western coastal town of Negombo and another church in the eastern town of Batticaloa - were targeted, police said. The blasts occurred at around 8.45 am (local time) as Easter Sunday masses were in progress, PTI quoted police spokesman Ruwan Gunasekera as saying.