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Lt. Srebalus said the crash happened near County Road 236 near Milam at about 8:07 p.m. Saturday.
Police said the victims, a 61-year-old, 17-year-old, and 5-year-old, were in the car driving northbound on Burnett Street when they encountered the train tracks.
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Witnesses told police that the car stopped on the track as the train approached and was hit, causing it to roll over and veer off the road.
Officials said that the road appears to have a bad line of sight and that traffic is not visible coming from the other direction. Officials believe the driver may have been looking for oncoming traffic and did not realize the train was coming.
Police noted a railroad crossing with a stop sign was at the intersection.
The 61-year-old suffered a head injury and had to be taken into surgery. His condition is unknown.
The 17-year-old also suffered a head injury but made it out of surgery. The 5-year-old is expected to be OK, officials said.
Officials said BNSF Railway Company is assessing the train.