Horsham Road, Crawley, is closed around the level crossing after a person was hit by a train.
British Transport Police were alerted to the accident at 9.53am today (Friday September 5) and police are diverting traffic away from the area.
The train involved was still at the level crossing at 11.45am as emergency services carried out their investigations.
Residents in the area were seen comforting one of their distraught neighbours who they said witnessed the accident.
A spokesman for BTP said officers were still on the scene and they hoped to have more information about the cause of the accident soon.
Southern Railway said: “Owing to a person hit by a train near Crawley all lines are closed while emergency services deal with the incident.”
The Brighton Road Level crossing is open.