Highway 4 in Walnut Creek was reopened Sunday after it was temporarily shutdown due to a suspicious explosive device.
According to California Highway Patrol, the device was rendered safe by Walnut Creek PD bomb squad.
Initially, a traffic alert was issued in Contra Costa County after the device was found Sunday, California Highway Patrol said.
CHP Contra Costa tweeted at around 1:30 p.m. that the device was found in a suspicious abandoned vehicle located off westbound Highway 4.
The incident remains under investigation.