Tens of thousands of rail passengers are facing major delays tonight after a person threatened to throw themselves off a bridge and onto the railway line at Wimbledon. It halted all services in and out of Waterloo for an hour.
The person was talked to safety and services have now resumed with delays likely to continue through the night.
The incident at around 3.30pm was at the start of the rush hour on one of the busiest tracks in the country.
Police and the fire service were called to the scene as all lines were closed. Passengers were stranded on trains for an hour.
South west trains say everything possible was done to clear the incident.
Delays of up to 50 minutes followed and services may now be subject to short notice cancellations or alterations. Delays are likely to continue until the end of service, the operator said.
Passengers are advised to use underground, bus, Southern and First Great Western services where possible.
A spokesman for South West trains said: "We are sorry for the disruption that our passengers will face this evening as a result and we have drafted in extra staff to help provide information to passengers at key stations.
"We are now doing our best to restore services as quickly as possible."
There's also been disruption this evening on Southern trains between Brighton and Portsmouth Harbour, and Haywards Heath and Littlehampton, due to a signalling problem at Worthing.
And delays of up to 45 minutes on the Gatwick Express between Gatwick Airport and Victoria due to broken down train at Thornton Heath. Normal services are not expected to resume until 8pm.
Earlier, a train was stranded at Ufton Nervet after hitting a man on a scooter on a level crossing.