Emergency services have rushed to the scene after a gas leak was detected.
Around 75 people have been evacuated from properties and all railway lines are currently closed between Andover and Salisbury, South Western Railway confirmed.
London Road remains closed between A338 and Hampton Park roundabouts and travel chaos is expected to last the rest of the day.
SWR said in a statement: "A gas leak is affecting the railway between Andover and Salisbury. Trains may be cancelled, delayed or revised because of this problem."
Wilshire Police said: "We have been notified of a gas leak in the London Road area of Salisbury.
"The road is currently closed and we would urge people to avoid the area. Thank you for your patience."
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