MAYWOOD, ILL., AUG. 27 -- Officials at Maywood Park Race Track say they still don't know how masked gunmen found a hidden accounting room at the track, let alone how they robbed it and got away.

"We're puzzled," Bill Moore, the track's assistant general manager, said Sunday. "It is safe to say they had some information because they were able to get in too smoothly. The source of the information is what puzzles us."

The masked duo took at least $20,000 in cash Saturday from the accounting room, despite secrecy about its location.

"It appeared they knew where it was. They circumvented a maze of stairs and doors," said police Capt. Arthur Jackson. "Employees there for two years often don't know where accounting is."

The robbery also was timed between betting periods, when few people are around the grandstands, Jackson said.

Before robbing the cash, the gunmen disarmed a security guard and disabled three employees with Mace, police said.

None of the victims required hospitalization, Moore said.

It was the first robbery since the track opened in 1946, track president Patrick Flavin said.

The race track was opened Saturday for simulcast wagering on races at other tracks. Races at the track in suburban Chicago begin Oct. 8.