Commuters are being urged to "remain clear" of East Croydon station after a "suspicious package" was found.
National Rail confirmed that trains were unable to stop at the station since around 4pm today (September 20).
Passengers were advised "not to travel" to the station as the incident was being dealt by police.
The station was evacuated and safety cordons were put in place in Addiscombe Road while specialist officers assessed the item.
As a precaution, specialist teams conducted a controlled explosion at the location.
Disruption is still expected to Southern, Gatwick Express and Thameslink services until 8pm.
This incident has now been stood down and police enquiries remain ongoing.
Thameslink posted on X (formally known as Twitter): "Police are dealing with an incident at East Croydon station.
"The main entrance is currently shut and you will need to use the alternative available entrances/exits at the station.
"Staff are on site and will help assist you should you need it."
A spokesperson for Metropolitan Police said: "At about 16:07hrs on Friday, 20 September, police were made aware of a suspicious package in Addiscombe Road, Croydon.
"Members of the public were evacuated and safety cordons were put in place while specialist officers assessed the item.
"As a precaution, specialist teams have conducted a controlled explosion at the location.
"This incident has now been stood down and enquiries remain ongoing."
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