Seattle police responded to 14th Avenue and East John Street at 5 p.m. after getting reports of a truck crash. When they arrived moments later, they found a 1989 Ford pickup truck resting on its side with a man stuck inside.
Investigators believe the man was driving westbound on East John when he lost control and hit a curb, causing the truck to roll.
The driver was briefly trapped inside the truck, but emergency crews were able to get him out and transport him to nearby Harborview Medical Center.
Police describe his injuries as "life threatening."
There were no passengers in the truck and the driver was the only person injured, according to police.
Traffic Collision Investigation Squad detectives responded to the scene and continue to actively investigate.