PHILADELPHIA (CNN/WTAJ) — A surveillance video shows the moment when a police detective shot and wounded an unarmed man in Philadelphia.

The man survived and is in critical but stable condition at the hospital.

The video shows Joel Johnson walking up to the detective’s unmarked car Monday night.

There is a blast of smoke as the detective fires through the car window and Johnson falls to the ground.

Footage shows him getting back up, but it looks like the officer tells him to get back down.

According to police, the detective thought Johnson was trying to carjack him with a gun, but investigators say he was unarmed.

HIs family also say he suffers from a mental disability.

The detective was placed on desk duty, pending an investigation.