A MELBOURNE teen allegedly modified a truck so convincingly he was able to fool other motorists that it was an emergency vehicle.

Heavy Vehicle Crime Investigation Unit detectives arrested the 16-year-old in the affluent beachside suburb of Brighton today after seeing online footage of the truck driving through traffic with emergency lights flashing.

The white truck had realistic looking flashing lights fitted on the roof as well as siren, horn and spotlight. It was so convincing motorists pulled to the side to let the vehicle through.

The boy had allegedly been responding to traffic crashes and even helped some people at the scene of accidents.

Police have estimated the value of the truck and modifications to be $100,000, according to 7 News.

The truck was mostly driven around the Melbourne suburbs of St Kilda and Elwood.

Victoria Police said the investigation was ongoing and the Brighton teen is assisting police with their inquiries. The truck has been seized by police.