VANCOUVER -- Police are investigating following what they describe as a serious assault in a Vancouver park.

In a news release Wednesday, Const. Tania Visintin said the assault was reported Monday night.

A man was found unresponsive in the Strathcona Park encampment after someone called 911, police say.

The person who made the call is unknown, and the man was found by B.C. Ambulance Services.

A witness told officials the man had been there for some time before paramedics were called to the scene. He was taken to hospital, where he remains in critical but stable condition, and police were called to investigate.

"This is a disturbing case considering how seriously the victim was assaulted and the length of time he was laying on the ground injured without any help," Visintin said.

Few details are known about the man, other than that he may be in his late 20s.

He has dark hair and a beard, and may be white or Indigenous, police said.

Anyone with more information is asked to call investigators or Crime Stoppers.