Motorists travelling on part of the M25 faced delays during the morning rush-hour following a crash believed to have involved a lorry and a pedestrian.
The motorway has been closed between junctions 3 and 4 in Kent since the collision at 3.30am today, Kent Police said.
The condition of the pedestrian has not been disclosed but drivers were warned to expect disruption on their journeys in the area.
A Kent Police spokesman said: "Emergency services are at the scene of the collision which is reported to have involved a lorry and a pedestrian.
"A diversion is in place but drivers are warned to expect delays."