Investigators are looking into the origin and cause of a fire at the Charles County Fairgrounds that resulted in about $500,000 of damage, officials said.

Firefighters were alerted to the blaze at 3:25 p.m. Tuesday. The fire spread quickly, and it took about an hour and a half for roughly 170 firefighters from Southern Maryland, Virginia and the District to get the blaze under control, according to the Maryland State Fire Marshal’s office.