Ottawa police are investigating a fatal stabbing in the city's downtown early Sunday morning.

They said they were called to the intersection of Rideau Street and Nelson Street around 12:55 a.m. Sunday, where they found a man who was unconscious and bleeding.

Ottawa paramedics said the man, possibly in his 30s, had been stabbed in the chest.

He was found without vital signs and taken to hospital while paramedics said they treated him with "aggressive resuscitative efforts" on the way.

Police said he was pronounced dead at the hospital.

Crews were still on the scene later Sunday morning cleaning up large blood stains left on the ground.

Police said there are currently no suspects in custody and are asking anyone with information to call their major crime section at 613-236-1222 extension 5493.