Someone has been hit by a train on the line between Brighton and Worthing.
And signal problems at Balcombe are delaying trains between Brighton and London.
Commuters travelling to Gatwick and London are facing delays of half an hour.
All trains have been cancelled between Brighton and Worthing after someone was hit by a train at East Worthing at about 6am this morning (Wednesday 30 July).
Replacement buses are running, according to train operator Southern Railway, but journey times are about an hour longer. First Great Western Services were also affected.
The National Rail website said: “A person has been hit by a train at East Worthing.
“Because of this, buses are replacing trains between Brighton and Worthing, with journey times extended by up to 50 minutes.
“There is no current estimate for when a normal service will resume.”
Southern’s sister company Brighton and Hove Buses said that it would accept Southern tickets on any reasonable journey between Brighton and Shoreham.
Update: Trains started running between Brighton and Worthing again at about 8am. Delays of up to half an hour were expected until about 11am.
Delays caused by the signalling problem at Balcombe were running at 15 minutes.
