Network Rail has issued an update after suddenly closing all railway lines between Horsham and Dorking.
In a statement on Twitter, the rail firm said the line closure was due to a landslip near Ockley.
A spokesman added: “We have a geotechnical engineer on their way but as yet, no estimate for reopening either line.
“Please check with @SouthernRailUK for travel information.”
A spokesman for Southern Rail said: “Ticket acceptance is in place to help you on your journey this afternoon:
“Metrobus route 93 between Dorking, Holmwood Park, Warnham and Horsham
“Great Western Railway between Dorking Deepdene and Redhill”
After Dorking, Holmwood, Ockley and Warnham will not be served with trains unable to run between Dorking and Horsham, he added.
The spokesman said: “We are in the process of arranging replacement buses.”