Rail travellers faced disruption during the rush hour after a train carrying seven passengers came off the rails at a level crossing in Norfolk.
Services were delayed by up to two hours after the incident
The derailment happened when the Norwich to Cambridge train operated by One Railway went across the level crossing at Croxton on Tuesday morning.
British Transport Police said the train struck a rubber paving block which had become dislodged on the crossing.
A One spokeswoman said no-one was injured in the incident near Thetford.
There were delays of up to two hours to the service between Norwich and Ely.
Some trains were cancelled and a bus service between Norwich and Ely was brought in.
Inspector John Clark, of British Transport Police, said that shortly before the derailment a motorist had tried to alert rail operators.
"Some other cars had swerved round this [paving block] and they were okay," he said.
"The driver came back and tried to alert people but unfortunately a train came by and struck [the block] and the train was derailed."
Network Rail said they had received a number of calls about the crossing and had sent an engineer out to inspect it on Friday.
A full inquiry will be carried out by Network Rail.