A Utah couple and their daughter were killed when a train plowed into their car in Clifton, Idaho, Sunday.

Killed were:Erick G. Johnston, 26, Providence, Cache County.

Charla M. Johnston, 29, Providence, Cache County.

Cassandra M. Johnston, 1, Providence, Cache County.

The train, traveling north at 50 mph, slammed into the passenger side of the Johnstons' sedan about 12:45 p.m. As the freight train came to a stop, it pushed the car along the tracks for about half a mile, said Idaho State Police Corporal Bob Laumann.

Erick and Cassandra Johnston suffered broken necks and died instantly, police believe. Charla Johnston died from internal injuries, Laumann said. The adults weren't wearing seat belts and the child was not in a safety seat.

"When the conductor got to the car, there were no signs of life," Laumann added.

The family was on the way to visit some relatives in Clifton, about 10 miles north of the Utah border. Investigators believe the driver, Erick Johnston, failed to see the train.

"My best guess is he just didn't see the train coming," Laumann said. "The conductor said the car slowed down but didn't stop at the tracks. He (Erick Johnston) crosses that train crossing all the time, and he's used to passing it without any trains. This time he was wrong."

The crossing is in a rural area and doesn't have flashing safety arms. The intersection has stop and train-warning signs.