Two psychiatric patients have been stabbed to death at an Australian psychiatric hospital and a fellow patient is being questioned by police.

The stabbings occurred late Wednesday at Thomas Embling Hospital in Melbourne. Police said Thursday that a 49-year-old patient armed himself with a large kitchen knife and stabbed his roommate and another man.

The man is expected to be charged later Thursday.

Detective Sergeant Wayne Cheesman said all three men had been convicted of murder.

Police were investigating where the man got the knife from.

The secure facility caters mainly for patients from the criminal justice system who need psychiatric assessment, care or treatment.