Wayne State University police officer Collin Rose is on life support and in "grave" condition with his fiancee and family by his side in a Detroit hospital, Wayne State Police Chief Tony Holt says.

"This is a very difficult day for me," Holt told reporters at press conference Wednesday morning. "In 40-plus years at Wayne State never thought have day like this."

Rose, 29, was shot in the head Tuesday evening while patrolling an area a few blocks off campus, near Martin Luther King Blvd. and Trumbull, in Detroit's Woodbridge neighborhood when he stopped to investigate a man, Holt said. It was unclear whether the officer had responded to a 911 call, although a woman who said she witnessed the shooting also said she'd called 911 about a troublesome man on a bike.

There had been a rash of car break-ins in the area the day before. Holt said he didn't know how that factored into Rose's decision to stop the suspect. The suspect, who is not being named by the Free Press because he has not been formally charged, was arrested late Tuesday night.

Related: Wayne State shooting suspect twice arrested on assaulting officers

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Police search the area where a police officer who works for Wayne State University was shot in the head while on duty near the campus Tuesday, Nov. 22, 2016, in Detroit.

The suspect is known to the Wayne State police and other area departments. In 2011, he was charged with two charges of felony assault involving a police officer, one causing injury, and pleaded guilty, resulting in a 53-day jail sentence, the records show. There also was an incident in 2014, Holt said, although he didn't have details of that.

The shooting is hitting the 65-member police department hard, university President M. Roy Wilson said at the press conference. At the press conference, many Wayne State officers, visibly shaken, gathered in the back and exchanged long hugs with each other.

Officials painted a picture of a dedicated officer when talking about Rose.

He was a 2010 graduate of Ferris State University and was one credit short of completing his master's degree in police administration at Wayne State. His first job was with the Richland police department in the Kalamazoo area.

He was a K-9 officer, who had both a bomb dog and a narcotics dog. Both were in his vehicle when Rose made the stop last night that led to his shooting.

Holt said it is common practice for the dogs not to be brought out on stops to control suspects.

Rose had worked and done and conducted training all over the state, Holt said. He was also heavily involved in organizing memorials for other slain police officers in the area. Members of many Detroit-area police departments showed up at the hospital last night and were there this morning.

This is the first shooting of a Wayne State officer in 36 years. That officer was shot in the leg.

"This is a tragedy of immense proportions," Wilson said, adding "Collin was doing his job. For that we thank him."