Medics and emergency crews responded to the scene, in the 14600 block of SE 176th Street in Renton, at about 4:30 a.m. after receiving a report of a "sparkler bomb" blowing up.
"I heard a bunch of screaming so I ran outside and there was some kid laying in the street who was bleeding," said Jack Lamb. "And there was blood going down the road."
The injured man was taken to Harborview Medical Center, where he was listed in critical condition with significant leg and arm injuries, said King County Sheriff's Office spokeswoman Cindi West. She said his left lower leg may have to be amputated below the knee due to the seriousness of the injuries.
A preliminary investigation found that the man had left a party in the Fairwood Apartments and ignited the device, made of at least 50 sparklers wrapped together with duct tape and wire.
The device exploded quickly, and the man was standing too close when it went off. The explosion was heard for several blocks and hurled debris up to 125 feet away.
Family and friends were present and provided immediate aid to the injured man. Renton Fire Station 17 responded and used a tourniquet for his left leg, which had open fractures below the knee. The man also sustained a deep penetrating wound to the left arm, West said.
The device was so powerful that it embedded wire fragments in trees across the street. Neighboring residents said the explosion was so loud that it woke them from a deep sleep and knocked out electrical power to some homes in the area.
The King County sheriff's bomb unit is investigating.