GRAND RAPIDS, Mich. — Grand Rapids Police are trying to identify four suspects in connection with a March 17 assault downtown that has left a man still unconscious.

GRPD posted surveillance video on its Facebook page Wednesday of the incident on Ionia Avenue at Cherry Street SW.

It shows some men walking across the road when one of them sucker-punches the victim, knocking him out cold in the crosswalk.

Police say the man was taken to a hospital with life-threatening injuries.

Sgt. Dan Adams tells FOX 17 there is no evidence the person who threw the punch had a weapon in his hand when he struck the victim, but police aren’t ruling it out either.

Grand Rapids police say in the social media post, “Witnesses observed an unidentified male punch the victim before another suspect picked up what is believed to be the victim’s cell phone.”

Police say the four suspects fled by walking away from the crime scene. Investigators are now looking to identify the suspects in the video. And they ask anyone who can help them do that to contact Detective Lewis at 616-456-4469, or contact Silent Observer.