A motorcycle crash on Tucson's north side closed a portion of East Fort Lowell Road, between North Dodge Boulevard and North Alvernon Way.
The motorcyclist suffered serious injuries, said Sgt. Kimberly Bay, a Tucson Police Department spokeswoman, in a tweet shortly before 4 p.m.
Traffic detectives will take over the investigation.
Motorists were asked to avoid the area.
No further information was immediately available.