A man was seriously wounded in a shooting Monday night in the Humboldt Park neighborhood on the West Side.

The 40-year-old man was standing on the sidewalk about 9:15 p.m. in the 2700 block of West Haddon when he heard shots and realized he’d been struck, according to Chicago Police.

The man was shot in the back of the head and took himself to Saints Mary and Elizabeth Medical Center, police said. He was being transferred to Stroger Hospital in serious condition.

A police source said the man is a documented gang member.