SALEM, Ore. (AP) — A fire broke out early Saturday at the Oregon state Capitol, leaving the building with smoke, water and fire damage, including to the governor's ceremonial office and the offices of some of his high-ranking staff members.

The fire, which started on the south side of the building, was reported by Willamette University students living across the street at about 12:30 a.m. Saturday, and was put out in about 20 minutes, said Capt. Calvin Curths of Oregon State Police. Five janitors working inside the building exited safely after being alerted by a fire alarm.

The blaze is being investigated as a possible arson, but a cause is not expected to be announced until after the holiday weekend.

The Oregon state Capitol burned down twice before, most recently in 1935. Extensive renovation work was being done on the Capitol this year, much of it in the area where the fire is thought to have started.

Most of building, which was added to the National Registry of Historic Buildings in 1988, escaped the blaze.