The gunman who walked into a Michigan police station and opened fire on Veterans Day was a 64-year-old military veteran in poor physical health and struggling with “internal issues,” police said Monday.

Harold Joseph Collins, of Southfield, Mich., was killed in a shootout with officers at police headquarters in Southfield on Sunday afternoon, authorities said. An officer was wounded in the exchange.

At a press conference Monday, Southfield Police Chief Eric Hawkins outlined the sequence of events that led to the shootout.

He said Collins, brandishing a .380-caliber handgun, walked into the lobby of the police station with a blank stare on his face; without warning he tried to shoot an officer behind bulletproof glass.

“The suspect approached the front desk officer and simply stared at the officer. The suspect appeared to be staring into the distance and not a word was said,” Hawkins said.

The weapon didn’t discharge. Other officers then quickly confronted the gunman.

“He was ordered several times to drop his weapon. The suspect refused.  Instead, he pointed the weapon at officers,” Hawkins said.

In the ensuing exchange, a 50-year-old police sergeant was shot in the shoulder. The gunman was shot several times and died.

Hawkins described Collins as a military veteran “who appeared to be in poor physical health” and may also have had psychological problems.

“Based on the behavior of this individual, in my opinion and in the opinion of investigating officers …this person was struggling with some very serious internal issues,” the police chief said.

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Hawkins said he didn’t know the gunman’s motive. Collins had no known criminal history.

“We can only speculate and right now I won’t, but yes, obviously yesterday was Veterans Day and we have information this person was a veteran. We have information this person was in poor health and had other internal issues.”

Hawkins wouldn't go into details about Collins' health issues but a former stepdaughter, Seretha Nobles, told the Detroit News on Monday that Collins had been suffering from throat cancer for many years.

"He couldn't speak, he can't talk," Nobles told the newspaper in a phone interview from her Georgia home.

Hawkins said the gunman arrived at the police department in a 2010 Dodge, which was later impounded for evidence. Investigators also planned to search the gunman's home for clues.

The wounded officer, whose name was not released, was “conscious, alert and in good spirits” at a hospital, Hawkins said. He was expected to be released later Monday or Tuesday.

All officers involved in the confrontation have been put on administrative leave per department policy pending an investigation.

Surveillance cameras in the lobby captured at least part of the confrontation, and the videos will be reviewed, the police chief said.

The shooting is being investigated by the Oakland County sheriff’s department. The Southfield Police Department will also do an internal investigation to make sure proper procedures were followed, Hawkins said.

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