WIBAUX, Mont. (AP) - A van veered off Interstate 94 and was struck by a train near here, killing two children and critically injuring another, the Montana Highway Patrol said.

The victims were Bianne Nelson, 5, and Finnerty Nelson, 1, of Spokane, Wash.

Conor Nelson, 3, was transported to a children's hospital in Minnesota, where he was listed in critical condition Tuesday night. The children's mother, Nina Nelson, 33, was taken to a North Dakota hospital and was listed in fair condition.

All four were reported missing Monday night by Nelson's husband, Thomas R. Nelson, Spokane Police spokesman Cpl. Tom Lee told The Spokesman-Review in Spokane.

Thomas Nelson told police that he last saw his wife and three children Monday morning when he left for work. Nina Nelson was preparing to take the children to run errands in Spokane, including a medical appointment for one of them, Thomas Nelson told police. They missed the appointment, he said.

During routine questioning, Thomas Nelson also told officers that he and his wife had not been having marital problems, Lee told The Spokesman-Review.

Emergency crews responded to the crash near the Montana-North Dakota border at about 2:15 a.m. Tuesday.

Preliminary reports said the van was eastbound on I-94 when it went off the road and drove through a right-of-way fence. It ended up on a BNSF Railway track, where it was hit by a train hauling coal.

Bianne and Finnerty Nelson died at the scene, Wibaux County Coroner Frank Datta said. Autopsies were scheduled for Wednesday afternoon in Billings.

Conor Nelson was taken to Gillette Children's Specialty Healthcare in St. Paul, Minn. Nina Nelson was transported to St. Joseph's Hospital and Health Center in Dickinson, N.D.

An investigation is under way; however, speed and alcohol were not believed to be factors, the patrol said. Nelson and the children were wearing seat belts, the patrol said.