VALLEJO -- Vallejo police are treating a suspected arson fire at the law offices of Vallejo Mayor Osby Davis early Saturday morning as domestic terrorism and have asked for assistance from federal investigators, fire and police officials said Saturday.

A Vallejo police spokesman told ABC7 that they are asking for FBI and ATF assistance to investigate the fire that gutted Davis' front office on Tuolumne Street across from the Solano County Superior Court.

"We're investigating it as arson at this time," Vallejo police Lt. Sid De Jesus said. "We don't know for sure, but we suspect it's an arson case ... The cause and origin is yet to be determined, but because it's an office occupied by the mayor, we're looking at this from every investigative aspect that we can."

Reached by phone, Davis said that to describe himself as "upset is an understatement."

He said he was awakened at about 1:30 a.m. by a phone call from fire Chief Paige Meyer and knew it was going to be bad news.

"Any time the mayor gets a phone call in the wee hours of the morning, it's never good," Davis said. "I really don't know what to say right now."

Davis said he will carry on.

"This is a bump in the road, a temporary hurdle," he said. "And we'll get past it and continue to do what we need to do."

It's too early to name a potential motive for the suspected arson, De Jesus said.

"We're not jumping to conclusions," the lieutenant said. "Both (Davis and Micheal Thompson) are high profile people. It could be a disgruntled client of either attorney that occupied that office." Thompson shares the office with Davis, and has been a judicial candidate.

Calling the blaze, which appears to have started in the front waiting room area, "very suspicious," Meyer said the single-story office building in the 400 block of Tuolumne Street, was about 50 percent involved when crews arrived shortly after 1:30 a.m. Saturday.

"We knocked it down within about 15 minutes, but the building looks like nearly a total loss," Meyer said. The contents, however, were mostly salvageable, he said.

This is the second incident in recent months in which the mayor has been the victim of a possible crime. On May 18, Davis' 11-year-old motorcycle was stolen from the City Hall parking lot.

De Jesus said police are asking anyone who may have been in the area at the time of the fire and think they may have seen something suspicious, to call the Vallejo police nonemergency number, 707-552-3285.