PORTLAND – Amtrak’s Downeaster passenger train service has a problem with snowmobilers – they get in the way, forcing emergency stops to avoid collisions.

The latest incident occurred Thursday night in Saco, when the train from Boston to Portland screeched to a halt to avoid hitting two snowmobiles, Amtrak officials said Friday.

Last month, the Downeaster nearly hit sleds in Biddeford, Wells, North Berwick and Dover, N.H., according to railroad police.

For years, snowmobilers have risked heavy fines to travel on the railroad, either on the tracks or on the service roads beside them. But the new passenger trains are quieter and faster than freight trains and officials with the railroad and the rail authority worry that someone is going to get killed.

“This is a wake-up call to the owners of all those sleds and the snowmobile clubs to get to their membership and keep them out of the right of way,” said Mike Murray, executive director of the Northern New England Passenger Rail Authority.

The problem is not confined to southern Maine. Last Saturday, a freight train hit three snowmobiles in downtown Newport. The riders, who were not injured, had been trying to get their sleds off the tracks when they saw the train coming.

Two years ago, a snowmobiler in Jackman was killed when a freight train struck him.

Thursday’s incident happened at 8:37 p.m. during the snowstorm. It was the first time a Downeaster train has used its emergency brakes since the service began on Dec. 15. There were about 200 passengers on the train. Nobody was injured.

The incident involved train No. 685, which leaves Boston at 6:15 p.m. and arrives in Portland at 9 p.m.

The train engineer saw the lights of the two snowmobiles as they rode toward the train, said Karen Dunn, an Amtrak spokesperson. She said the engineer blew the horn and activated the emergency brakes.

The engineer initially thought the train had struck one of the sleds, but he later said that neither sled had been hit, according to Michail Grizkewitsch, an officer with the Boston and Maine Railroad Police. He said two sets of tracks had been left in the snow, but he couldn’t follow them on foot because of the storm.