The homicide unit was brought in to investigate a serious assault of a man in northwest Calgary.

The man, said to be in his 60s, is in hospital in critical condition.

Police say they were called to the community of Royal Oak just before 2 a.m. MT Sunday.

The man was taken to hospital in life-threatening condition. Police say his condition has not improved. His injuries are so serious, homicide detectives have been called in to investigate

A man believed to be in his 40s is in custody.

Neighbours say the injured man rents a room in a home owned by the man in custody. Police still have that home taped off.

High number of assaults

Meanwhile, Calgary EMS say they were called to an unusually high number of assaults overnight Saturday.

EMS spokesperson Stuart Brideaux says that between 6 p.m. Saturday night and 9 a.m. Sunday they had 16 calls from all quadrants of the city.

"EMS does attend to assaults on a daily and nightly basis to various degrees, but certainly, inside of one night shift, to be going to this many assault calls is unusual, to the extent where, at times, two or three of them were actually occurring at the same time."

Brideaux says the calls were all unrelated, so he can't draw any conclusions about why it was so busy.