The southbound train, on its way from Seattle (search) to Portland (search), was crossing a bridge over the river when the accident occurred in a rural area about 13 miles north of Vancouver in southwest Washington.
Arin Kight, 30, and Ashley Falk, 12, both of Ridgefield, were killed, the Clark County sheriff's office said Monday night. The Clark County medical examiner's office put the dead man's age at 33 and there was no immediate explanation for the discrepancy.
John Bromley, a Union Pacific spokesman in Omaha, Neb., told The Associated Press by telephone that the group of people was trespassing on the bridge, which he described as private property and "not a pedestrian passageway."
Gus Melonas, a spokesman for Burlington Northern Santa Fe, said the train with 47 rail cars struck the man and the 12-year-old child, who was his neighbor, near the middle or south end of the bridge.
The sheriff's office identified the injured children as 12-year-old Heaven Campbell, 7-year-old Matt Thompson, and 6-year-old Wayne Frye. Their hometowns and relationships were not immediately released.
The bridge links Ridgefield and the town of Woodland, directly to the north. The only land route involves driving a car on Interstate 5, said local resident Joel Natterstad, 28.
Until about five years ago, an 8- by 8-foot plank jutting out from the tracks provided a safe haven for those crossing the bridge if a train came, he said, but it was removed.
Bromley said Union Pacific would investigate. Melonas said Burlington Northern, which owns the tracks, also was investigating.