Cleveland and Durham Specialist Operations Unit are appealing for anyone who may have witnessed a collision in Stockton.
The incident involving a blue Vauxhall Vectra at the roundabout junction of Concorde Way and 1825 Way at around 4am on Wednesday.
The vehicle mounted a kerb, collided with a road sign and then caught fire. All three men in the vehicle managed to get out of the car.
The driver, a 27-year-old man from the Yarm area, suffered internal injuries, one man from the Thornaby area suffered a serious head injury and another man from the Thornaby area, aged 30, suffered a leg injury.