ELMONT, N.Y. (AP) _ Two horses were fatally injured and a third burned Tuesday night when a fire broke out in a barn housing 40 thoroughbred race horses at Belmont Park.

Three civilians sustained minor injuries, according to a Nassau county fire official.

The fire started at the Barn 8 annex at approximately 6:20 p.m., several hundred yards from the barns of Hall of Fame trainers D. Wayne Lukas and Scotty Schulhofer. More than 2,000 horses are kept in 64 barns at the sprawling 430-acre complex, the largest race track in the nation.

According to eyewitnesses, including a groom who ran in to save several horses, flames shot ``from one end of the barn to the other'' on the ceiling above the stalls, activating the sprinkler system. Dozens of track workers converged on the scene, and led the rest of the horses to safety.

The fire was extinguished completely by 7:10 p.m., according to NYRA officials.

``We lost two and one was seriously hurt and a few others were probably affected as well by smoke inhalation,'' NYRA fire marshal Kenny Kopp said. ``But it could have been worse. Much worse.''

The dead and injured horses were all trained by Jimmy Toner. The horses euthanized by veterinarian Dr. Stephen Selway were Graceful Finish, an unraced 2-year-old daughter of Dixieland Band owned by John and Joan Phillips, and Clear to Launch, a 3-year-old gelding owned by Caesar Kimmel.

The injured horse, Surely Handsome, a 3-year-old co-owned by Kimmel and Ron Nicholson, was returned to another barn after being treated by Selway. The horse was later reported by Toner to be ``resting comfortably.''

It was the first major fire at Belmont Park in more than 13 years. In 1986, 45 thoroughbreds died in a fire at Barn 48, 36 of them trained by John Campo Sr., who trained 1981 Kentucky Derby and Preakness winner Pleasant Colony.

The cause of Tuesday night's blaze was under investigation.

``To speculate how it happened would be an injustice,'' Kopp said as he stood outside the front gate of Belmont Park. ``We don't know. It could have been a cigarette or something.''

Smoking is prohibited inside the stables.

``The origin of the fire is not known at this time,'' NYRA president and COO Terry Meyocks said. ``This is a terrible tragedy, but we are grateful the sprinkler system and fire alarm worked perfectly, thus preventing any further loss.''

Clear to Launch was to have raced on June 16 at Belmont, but was scratched. Surely Handsome last raced June 10 at Belmont, finishing sixth in a maiden claiming race.

The barn, which is a receiving barn for horses not usually stabled at the track, had a lot fewer horses in it than normal because there is no racing at the track on Monday and Tuesday.

Fire companies from four nearby towns and the track's own emergency service responded to the alarm.

``The response was very quick and the sprinklers in the barn worked,'' Kopp said. ``People from track and those responding from outside very slowly took the horses out.''

Ronnie Hardin, a groom for trainer Pat Kelly whose horses are in the barn next to the one that caught fire, was among the first people on the scene.

``All of a sudden there was this blaze in J.J.'s barn,'' he said, referring to Toner. ``It was in the ceiling of the stalls. It shot from one end to the other and the barn was all blackened. When I went through I saw a horse lying burnt and didn't go for that one but we got one out and the one we got out his face was all burnt. We walked him until someone took him from us.

``I just had to go in and get those horses. They're in captivity behind that webbing and can't do anything.''

On Jan. 15, 1996, What an Evening, a 3-year-old colt, was killed in a Belmont stable fire that he started when he reared and toppled a heat lamp which set some hay on fire.

A month-long investigation never determined a cause for the 1986 fire although a heat lamp in a stall where hay was piled too high was considered a possibility.