Police are trying to trace a large group of youths who let off two fire extinguishers on a train on Saturday.
The youngsters were later spotted behaving anti-socially at Church and Oswaldtwistle railway station.
British Transport Police said the group had also caused problems for passengers while they were on the train.
A spokesman for BTP said: "Shortly before 10pm on Saturday, October 27 we were notified of a disturbance at Church and Oswaldtwistle rail station.
“Officers attended, alongside colleagues from Lancashire Police, and discovered a large group of youths behaving anti-socially at the station and on-board a train at the platform.
“The youths had boarded the train, a Blackpool South to Colne service, at Blackburn and during the journey had caused problems for other passengers and let off two fire extinguishers.”
The spokesman added: “We are now working with Lancashire Police and rail staff to trace those responsible.
“If you have any information about the incident please contact British Transport Police on 0800 40 50 40.”