A man and his wife seeking to dispose of a suspicious device brought the item to the CHP headquarters in Old Town Tuesday morning.
The device was an "unexploded mortar round," which was non-operational, according to authorities on the scene.
The couple that brought the device drove it in a van and parked it in the CHP headquarters visitor lot on the 4000 block of Pacific Highway.
A Bomb squad investigated the device and determined it was "non-live."
The man said he and his wife were cleaning out his father's garage when they found the device. They believed it was a war relic. Investigators said the device was not illegal.
The intersections of Pacific Highway and Friars Rd., as well as Pacific Highway and SeaWorld Dr. were shut down while the fire department's bomb squad responded to the incident.
The parking lot of the headquarters was also shut down, but the building was not evacuated.
An bomb expert on the scene said if someone finds a potentially explosive device, they should leave it where it is and call the fire department.