Unconfirmed reports suggest two people have been killed in north Belfast.
A local councillor said he understands they were stabbed.
There is a heavy police presence outside flats at Kinnaird Close and some residents have been asked to leave their homes.
The area has been cordoned off as police forensic officers examine the scene. The alarm was raised in an emergency 999 call.
The Northern Ireland Ambulance Service were called to the scene at about 13:00 GMT on Monday.
SDLP councillor Paul McCusker said he understood that a man and woman had been killed.
Mr McCusker said it was "horrific news".
"There is a sense of shock across the community, a lot of anger, a lot of sadness," he said.
"Lots of children and lots of families live in this area. It is fairly settled."