Vandals who threw a missile onto the rail tracks in York caused “significant disruption”.
British Transport Police said an orange marine buoy was thrown from the Water End bridge onto the railway.
It happened at 5pm on Friday, 8 January.
“The buoy became entangled in the overhead lines before being struck by a train, causing significant network disruption,” a spokesperson said.
If you witnessed the incident, or have any information, please contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 272 of 08/01/21.
Alternatively, you can call Crimestoppers anonymously on 0800 555 111.