Rush-hour train services were disrupted today after someone reportedly started firing shots at trains in the Finsbury Park area – one of them injuring a passenger after it shattered a train carriage window.

British Transport Police confirmed an “object” struck the 3.52pm Moorgate to Stevenage service, injuring a passenger in the ear.

A spokesman for train operator First Capital Connect said four trains in total had been “affected”, and reports on Twitter suggest at least one has been taken out of service after arriving at Finsbury Park station with a window shattered.

Luke Morris tweeted: “Unbelievable scenes... Madness at Finsbury Park because of some f’ing idiots shooting at trains. Love to get hold of them #cowards.”

While no official channels confirmed the cause of the incident, train drivers announced to passengers that someone with an air rifle was targeting the trains.

This afternoon @finsbury_pk tweeted: “I’m on a train outside FP, stopped at red light – driver announced backlog due to someone taking potshots at a train with air rifle earlier!”

Officers from British Transport Police (BTP) attended the line at 4.14pm. A BTP spokesperson said: “An investigation is under way to establish the full circumstances and officers are appealing for anyone with information to contact British Transport Police on Freefone 0800 405040, or the independent charity Crimestoppers on 0800 555111.” Quote incident 426 of 26/04/13 in any calls.