An investigation is underway after a woman was stabbed multiple times this morning in downtown Birmingham.

North Precinct Sgt. Earnest Lockett said the incident happened about 5 a.m. on 16th Street North between Second and Third avenues. She was found on the sidewalk and taken to UAB Hospital, where she is undergoing surgery.

They have not released the name or age of the victim, but said her injuries are life-threatening. Birmingham police spokesman Lt. Sean Edwards said the victim and the suspect know each other, and both are regulars at the Firehouse shelter.

"Witnesses said the suspect gets angry from time to time,'' Edwards said. "It is believed the suspect just lashed out at the victim, stabbing her multiple times. "

The suspect is in custody pending a formal charge of attempted murder.

Updated at 12:07 p.m.