RAWLINGS — Fire investigators are trying to determine what sparked a blaze early Sunday morning that caused extensive damage to a vacant building that once housed the Rawlings Athletics Complex.

One hundred firefighters from volunteer fire companies from around the area were alerted to battle the blaze, which was first reported to the Allegany County 911 Joint Communications Division by a passerby at 1:59 a.m. The building is located on Racquet Club Drive, near U.S. Route 220 and adjacent to the Fore Sister Golf Course.

Where exactly in the 200- by 150-foot building the fire started also remains a mystery, investigators said.

Firefighters brought the fire under control in about an hour and a half and were on the scene for more than three hours, according to a press release from the Maryland State Fire Marshal’s Office. The last firefighting unit cleared the scene at 5:20 a.m.

Investigators estimate $500,000 worth of property damage — $400,000 to the building and another $100,000 to the contents inside.

Firefighters from Rawlings, Cresaptown, McCoole, Clarysville, Baltimore Pike, Westernport, District 16, LaVale, Bowling Green, Bedford Road, Ellerslie, Mount Savage, Barton, Bloomington and Frostburg fire departments, as well as LaVale Rescue Squad responded to the scene, as did nearby West Virginia crews from Short Gap, Ridgeley, Wiley Ford, Keyser and New Creek.

Allegheny Power also sent a crew to the scene.

The complex was built in 1978. When it functioned as the athletic complex, it included a full-sized outdoor swimming pool, athletic fields and indoor tennis courts. The courts were used often for indoor soccer tournaments.

The property was bought at auction in September 2006 by Vincent Groh of Hagerstown for $748,000. Groh could not be reached for comment Sunday night.

The building also formerly housed the Rawlings Racquet Club.

The fire marshal’s office is asking anyone with any further information on the incident to call (301) 791-4758 or (301) 729-5021.