MEDFORD -- Police have set up a perimeter at the district attorney's office in Medford after an explosion about 4:30 a.m., according to KOBI TV.
The station reports that an unspecified explosive device detonated near or on a propane tank. The blast shattered windows.
A man in dark clothing several blocks from the scene ran from an officer and has not been found, Medford police Lt. Mike Budreau told the Mail-Tribune newspaper. It's not known if he has a connection to the blast.
Arriving officers saw a large propane tank on fire, Budreau told the newspaper. Damage was mostly on the exterior of the building, at 715 W 10th St. Had the tank fully detonated, it likely would have destroyed most of the building, he said.
Nobody was in the building. Police believe the detonated device was the only one in or near the building, KOBI reports.
Police said they have no leads yet. The FBI and ATF were on the scene as part of the investigation.