Some passengers are believed to have been injured after a crash involving two trains in Salisbury.
The incident happened when a train carriage was derailed after hitting an object, and a second train then collided with it when signalling was affected.
There were unconfirmed reports that a train driver is trapped at the scene.
Emergency services are at the site close to London Road, Salisbury, Wiltshire Police said.
Sources said up to a dozen passengers are believed to have been injured, describing them as “walking wounded”.
A Network Rail spokesperson said: “At around 7pm this evening, the rear carriage of the 1708 Great Western Railway service from Portsmouth Harbour to Bristol Temple Meads derailed after striking an object on its approach to Salisbury station.
“The derailment knocked out all of the signalling in the area. Subsequently, the 1720 South Western Railway service from London Waterloo to Honiton then collided with the Bristol train.
“There are reports of injuries and the emergency services are on site along with railway first responders.”
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