DETROIT -- An 82-year-old man on Detroit's northwest side shot and severely wounded an intruder who walked into his Collingwood Street home Sunday afternoon.

Police said that the intruder, a 44-year-old man from Redford, was visiting friends in the neighborhood when he entered the home of Thomas Jackson, 82, and his wife.

Jackson grabbed his gun and shot the intruder.

Police are investigating why the man had entered the home, but a friend told Local 4 that the intruder has a history of mental illness

"What he does, he's been known to go into people's houses and just sit down," said friend Charles Smith.

"He don't know where he is. He'll go into people's cars and sit down, you know, follow strangers down the street."

The intruder was listed in critical condition at Henry Ford Hospital Sunday evening.