It was the second derailment on the same route in a month. State Railway of Thailand governor Prapas Jongsanguan said the overnight train from Bangkok to Chiang Mai skidded off the tracks early today in Phrae province. Seven out of 10 carriages flipped onto their sides.
Railway authorities believe the accident was caused by old tracks that were scheduled for repair.
Prapas said one passenger was seriously injured. The rest suffered minor injuries and were provided free transport to their destinations.
The Bangkok-Chiang Mai train is popular among foreign tourists.