A passenger train from Chiang Mai to Nakhon Sawan rammed at a herd of stray buffaloes on Wednesday night killing 21 of them.
The incident happened at about 8.00pm last night as the train running from Pak Nam Pho railway station was about two kilometres before arriving at Nakhon Sawan railway station.
The incident delayed the train for almost three hours as some of the train wheels jumped off the tracks and some cars were damaged.
Railway workers have to remove the carcasses of the killed cattle and placed them by the sides of the railway tracks.
Other trains scheduled to pass the scene were all delayed.
The train was put back to service before midnight.
Witnesses said the train driver whistled as he saw the cattles coming on to the tracks and blocked its way.
Railway officials and police are finding the owner of the cattle to take responsibility for the damages.