Tuesday’s fire in the Hamilton Complex’s Dunn Hall was an accident caused by mop heads catching on fire, investigators have confirmed.

The fire, which began at approximately 11 a.m. on Tuesday morning, started in the basement of Dunn Hall. According to investigators, a spontaneous combustion was caused by cooking oil residue on mop heads left in a custodial bucket. The mops had been washed and placed together after coming out of a hot dryer.

A damage estimate for the Dunn Hall basement has not been completed.