The A421 remains closed westbound between Marsh Leys and Marston Moretaine after 600 litres of diesel was spilt on the carriageway.
At around 3.20am a red Mini Cooper was involved in a single-vehicle collision after losing control on the road.
Shortly afterwards, a lorry collided with some of the debris from the incident, causing a fuel spillage.
The road is estimated to be closed for a significant period of time in order to make the scene safe. Motorists are asked to avoid the area and seek alternative routes where possible.
A police spokesman said: "We are appealing for anyone who witnessed the incident or has any information to contact us on 101, quoting the reference 37 of 16 May."