Seattle police are investigating a shooting Monday in the South Delridge neighborhood that left a 24-year-old man with serious injuries.

The man had been delivering an item sold on a secondhand-goods website near the 9000 block of 18th Avenue Southwest around 2 p.m. when he called 911 and said he had been shot, according to a statement from Seattle police.

The victim was taken to Harborview Medical Center in serious condition, said Seattle Fire Department spokesman David Cuerpo.

Officers, along with deputies from the King County Sheriff’s Office, did not locate the suspect. The police department released surveillance video Tuesday it said shows the robbery and asked the public for help identifying the suspect. In the video, a man approaches the victim and pulls out a gun out of his pocket, pointing it toward the ground as he begins talking to the victim.

Robbery detectives are investigating.