KANSAS CITY, Mo. -- A man has critical injuries after a stabbing Monday night, police said.

An officer on patrol in Midtown said he knew something was wrong when he saw a man doubled over on the sidewalk, and several people scattering.

It happened near the Armour Flats Apartments at Armour Boulevard and Holmes Road.

A witness said a group of men pulled up in a car and start arguing with another group. He said he didn't pay much attention until a few minutes later, when a man walked toward him bleeding.

"It didn't scare me as much as I thought it would. I was just worried if anyone would get here to help. But police were on the scene before you could snap your finger. I guess someone was on patrol here. It makes you feel safe that police could've been here that quick," said John Dirnberger.

Officers arrested four people in all. They said it's unclear what that argument was about.