London police are investigating after a stabbing late Monday in the city's south end.

Emergency crews were called to 91 High St., just after 11:50 p.m. for reports of a stabbing.

Police say they found a 22-year-old man in the hallway with multiple stab wounds in the abdominal area.

"He was transported to the hospital where he remains in serious condition," says Const. Ken Steeves.

"There’s indication that the altercation occurred within the building."

Robert McNicol was visiting a friend in the building and saw part of the crime scene.

"I kind of looked around and I noticed blood drops, just on the inside of the door," he says.

A 21-year-old London man was arrested later in the day, nearby without incident.

Blaine MacKenzie of London has since been charged with one count of aggravated assault.

The two men were not known to each other.

An investigation continues, but police say no other suspects are being sought.