The bodies were discovered about 2:30 p.m. when deputies sent two robots inside the office at the Indian casino following an hours-long standoff, Sheriff Bill Gore said. Officials had not yet released any details about the victim.
The ordeal began at about 10 a.m. when Donnell Roberts, 38, of El Cajon, burst into the office with a shotgun and ordered three secretaries to leave, sheriff's spokeswoman Jan Caldwell said. Witnesses heard three shots.
Robert was fired from a security job with the tribal gaming commission and was previously a casino guard, Caldwell said.
About 15 people left the offices, which are located in trailers or bungalow-type buildings behind the main casino, Caldwell said. Sheriff's deputies, California Highway Patrol officers and tribal police surrounded the building where Roberts was holed up. FBI agents also arrived.
By early afternoon authorities had yet to establish contact with him, Caldwell said.
The casino's general manager, Rick Salinas, said the casino remained open.
Salinas said he didn't know why Roberts was fired from the commission, which functions as the tribe's regulator of its casino. Roberts was one of several regulators working for the commission, he said.
"He was a professional, he did his job, and from my understanding he did it well," Salinas said.
The general manager said he hugged several commission employees.
"They're all pretty shaken up," he said.
The resort, which includes a 400-room hotel, golf course and spa, is operated by the Barona Band of Mission Indians.
The tribe bought the reservation property in 1932 after its original reservation land was used to build a reservoir. Tribal gaming began there in 1994 with the opening of the Barona Casino Big Top.
The five-member gaming commission meets about three times a week, said Sheilla Alvarex, director of government affairs for the tribe.
Commission members are not all tribal members but they are employees of the tribal government, Salinas said.
"They are responsible for ensuring that the management team is complying with all regulations," she said.