Lives were put at risk by yobs who placed shopping trolleys on a railway line near Sheffield.
Two trains struck trolleys which were placed on tracks off Station Road, Killamarsh, on the same night.
British Transport Police has branded the prank as ‘reckless’ and said people could have been killed.
Officers were alerted to the incidents between 9.50pm and 11.40pm on Sunday, November 29.
When they examined the trolleys placed on the tracks they found that one contained concrete blocks.
PC Ewan Brechin said: “The 9.50pm East Midlands Trains service from Nottingham to Sheffield struck a Morrisons supermarket trolley which had been placed between the rails, causing the train to come to an emergency stop.
“At 11.40pm a freight train travelling in the opposite direction also struck a Morrisons supermarket trolley which contained concrete blocks. Again, the train came to an emergency stop.
“Neither trains were damaged but the incidents resulted in 32 minutes of delays.
“Both drivers were extremely shaken up by what happened.
“The consequences of such reckless actions could have been far worse and resulted in serious injury. Placing obstructions on the railway is, simply put, putting lives at risk.”
Witnesses or anyone with information about the incident should call British Transport Police on 0800 405040 or Crimestoppers, anonymously, on 0800 555111.