ATLANTA (CNN) -- A Delta Air Lines flight was delayed Thursday after passengers and crew members discovered cockroaches loitering near the plane's food service area, a newspaper reported Friday.

Airline officials delayed Flight 217 from Atlanta to San Francisco for more than three hours. The flight was scheduled to leave about 9:15 a.m., but passengers and crew spotted the roaches shortly after boarding, according to The Atlanta Journal-Constitution.

The pilot refused to fly the plane, said Delta spokeswoman Laura Gillig, and the passengers flew out of Hartsfield International Airport about 1 p.m. on another plane.

Delta called it "an isolated incident." Finding roaches on a plane is very unusual because exterminators usually spray passenger planes during layovers between flights, Gillig said.

The Journal-Constitution reported that Delta officials did not know Thursday how the roaches got on board the Lockheed L-1011 plane and that airline representatives were discussing the incident with the pest control company and Dobbs International Services, which provides meals for Delta flights.

The newspaper quoted Gillig as saying: "You thought the Year 2000 bug was bad?" Let me tell you..."