He was being chased by someone who works in the service station when he fell and was struck by the vehicle.
Police received reports of a theft at the Tesco Express shortly before the collision.
They were called at 3.40pm to reports of a collision between a man and a lorry outside the Tesco on North Road on Thursday 10 January.
The victim, a man in his 30s, was taken to hospital by emergency services with serious leg injuries.
Officers also arrested a 39-year-old man from South Ockendon on suspicious of driving under the influence at the scene.
Enquiries are ongoing.
Tags: Thurrock, South Ockendon
