By Teresa Carson
PORTLAND, Oregon (Reuters) - A propane gas tank rigged as a homemade bomb exploded in flames outside a prosecutor's office in Oregon on Wednesday in a pre-dawn attack that police said was being investigated as an act of domestic terrorism.
No one was hurt in the blast in the town of Medford in southwest Oregon, which occurred at about 4:30 a.m. local time (7:30 a.m. EST) in front of the Jackson County District Attorney's Office, across the street from the county courthouse and jail, authorities said.
The incident was believed to be the first bombing directed against a government agency in the area, and investigators were looking for possible ties with a number of cases the district attorney's office has prosecuted, Medford police Lieutenant Mike Budreau said.
No arrests have been made, he said. Police saw a man dressed in dark clothing about a half mile from the scene of the explosion who ran away when approached by officers, but investigators are not certain he was connected to the bombing.
"It's suspicious behavior for being in the general area, but not so close (to the blast) where you think, 'That's the guy,'" Budreau said.
Police responding to the blast office found a damaged seven-gallon propane tank ablaze and flames shooting up the outside of the building, as well as broken glass from shattered windows, police and the FBI said.
The fire went out on its own, and damage to the single-story brick building was confined mainly to the its exterior, police said.
"We believe the suspect tried to detonate the propane tank with an improvised explosive device (that) damaged the propane tank," Budreau told Reuters, adding that the tank caught fire but remained mostly intact.
While the motive behind the bombing remained unknown, police and FBI said the prosecutor's office appeared to have been deliberately singled out for attack.
Asked at a news conference whether he regarded the bombing as an act of domestic terrorism, Police Chief Tim George replied, "Yes."
"The explosive device was clearly intended to target a government facility, the D.A.'s office," the FBI in Portland said in a statement. "An attack on such a visible symbol of government and justice demands our singular attention."
In addition to Medford police and the FBI, investigators from the Oregon State Police, the federal Bureau of Alcohol, Tobacco, Firearms and Explosives and the Jackson County Sheriff's Office are involved in the investigation.
(Reporting by Teresa Carson in Portland; Additional reporting by Chris Francescani in New York and Steve Gorman in Los Angeles; Writing by Steve Gorman; Editing by Cynthia Johnston, Leslie Gevirtz and Ken Wills)