Arson is believed to have been the cause of two minor fires that damaged the Thomas Jefferson High School lower auxiliary gymnasium last week, according to South King Fire and Rescue officials.

SKFR quickly responded and contained the fires that filled the gym with smoke on Monday, July 1, and Thursday, July 4. The high school has an Auburn address and sits in unincorporated King County.

The King County Sheriff’s Office investigated, suggesting the fires are likely the work of an arsonist.

Damage from the fires is preliminary estimated to be in excess of $100,000, said Gordon Goodsell, SKFR assistant chief. However, the school district’s cost estimate for repairs is $50,000 or less, said Kassie Swenson, chief of communications for Federal Way Public Schools.

The fires came as construction crews continue to perform preliminary site work for the school’s rebuild, which is scheduled to begin in winter 2020. TJ is one of eight schools to be renovated in the district, part of the 2017 voter-approved, $450 million school construction bond.

Repairs are expected take two weeks or less to complete, and bond dollars will not be used to pay for the repairs, Swenson said.

“We are thankful for our local fire department and law enforcement partners to help maintain safe and secure school campuses,” she said in an email.

Anyone with information about the fires is asked to contact the sheriff’s office at 206-296-3311.

The Arson Alarm Foundation may award up to $10,000 to anyone who provides information leading to a conviction in this case.