Rail passengers between Newcastle and Middlesbrough were given a fright after a window on the train was shattered as it passed a Metro train.
The incident took place on the 6.30pm service in between Newcastle Central Station and Sunderland train station.
Witnesses said there was a loud bang as the trains passed on the line as the outer pane of the double-glazed window was broken, leaving them unsettled.
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Rail operator Northern have said the trains did not collide and explained that a damaged window on the Metro came away and hit the other locomotive.
A spokesman for the company said: "There was a stone throwing incident at Brockley Whins, where a Nexus train got its window broken.
"It was returning to the depot and it passed one of our trains, the rest of its window fell out and hit our train.
"It has cracked the outer window. We inspected the train at Sunderland and it was fine to go on. It will carry on to the end of its journey, then it will be taken out of service and repaired."
Passenger Sarah O'Connell said: "There was a very loud bang and the train hasn’t sounded the same since. Everyone is really worried," and added that she had thought the trains had actually collided - although Northern confirmed this was not the case.
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