WORCESTER, Mass. (AP) — Worcester police are investigating a shooting that left a 15-year-old boy in serious condition.

Officers responded to a Sigourney Street address at about 8:20 p.m. Wednesday where they found the boy leaning on a picnic table suffering from multiple gunshots wounds. He was conscious and alert when police arrived.

He was taken to a hospital and is expected to survive.

Witnesses told police that the victim was sitting on the picnic table when the assailant approached from behind and started firing, then fled on foot.

The suspect was described as a male, about 17 to 20 years old, approximately 5-foot-8, wearing a sweatshirt with black pants and carrying a backpack.

There have been no arrests and police say they do not know the motive.