Two men were found injured on the tracks at a busy station causing severe delays for rail commuters.
British Transport Police (BTP) is investigating but said it was not yet clear how the men came to be on the railway line in an area at the north end of Birmingham New Street station today.
The incident caused disruption to services in and out of the station from 6am.
A police spokesman said: "Officers from BTP West Midlands attended Birmingham New Street station after reports of two men on the railway line. Words:PA
"Medics attended and administered first aid to the men at the scene."
He added: "At this time it is unclear how the men suffered their injuries and the incident is being treated as unexplained, while officers continue inquiries and establish the full facts as to how the men came to be on the tracks."
The police have urged anyone with information to call on 0800 405040.
The incident meant some Arriva Trains Wales, CrossCountry and London Midland rail services were running with delays up to 20 minutes, according to National Rail Enquiries.
Network Rail said normal running had resumed but cautioned rail passengers to expect some residual delays between Birmingham and Wolverhampton.
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