A Bayport-Blue Point High School student was struck and killed by a Long Island Rail Road train yesterday, becoming the third student from the school killed by trains this year, authorities said.

Emma Casey, 15, a 10th grader, was struck at 3:37 p.m. by a westbound train 50 feet west of the McConnell Avenue crossing in Bayport.

"Unfortunately, this is becoming all too frequent," James March, the school board president, said. "This is the fourth student we've lost this year for different reasons," including the death of a student from cancer.

In November, a 14-year-old girl was killed when she walked in front of a LIRR train near the Snedecor Avenue crossing. Her death was classified as suicide.

In March, Lucas Svoboda, a 10th-grader, was killed accidentally after he ducked under a crossing gate at Gillette Avenue and tried to beat a train across the tracks.

Brian Dolan, a spokesman for the railroad, said the circumstances surrounding Casey's death yesterday were unclear. There was no pedestrian crossing at the location where she was struck. A determination on the cause will not be made until after the medical examiner's report, he said.

Dolan said the LIRR has presented its railroad safety program in the school district, and will do so again if the school district asks.

March said, "I know the Long Island Rail Road has been very cooperative. There's no easy answer to this. Right now we'll have to turn to the professionals to try to help."

He said counselors would be available today at the school for students and staff.

"I can't imagine having to endure losing four students," March said.