Passengers lives were put in danger after a ball bearing was fire on a Sheffield train.
British Transport Police (BTP) is appealing for witnesses after the incident that resulted in a shattered a window.
The incident happened at around 5pm on Bank Holiday Monday, May 25, as the 4.13pm Northern Rail service from Huddersfield to Sheffield travelled between Dodworth and Barnsley stations.
Investigating officer PC Ewan Brechin said: “As the train passed the recreation ground off Pogmoor Road, a ball bearing was fired at the train. On impact it shattered the laminated safety glass.
“Fortunately, no one was injured but passengers on the service were left extremely distressed and alarmed by what happened.
“The train driver was made aware of what had happened when the service reached Barnsley station, causing it to be delayed for around 10 minutes.
“This was an extremely serious and reckless act which endangered the lives of passengers and the driver, not to mention the delay and inconvenience caused to rail users.
“It is vital we find those responsible for this and I would urge anyone with information to contact us immediately.”
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference PSUB/B14 of 29/05/2015. Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.