Man causes high speed horror crash in tunnel by grabbing the wheel of moving bus before driver can react

Terrifying video shows a man suddenly grab the steering wheel of a moving bus and force it to swerve into the side of a tunnel.

The footage, seemingly taken on a security camera inside the bus, shows the attacker grab the wheel, causing the bus to lurch to the left in spite of the driver's efforts to fight him off.

Passengers are seen being sent flying forward as the bus smashes at a high speed, and luggage comes tumbling from overhead compartments.

Unverified video also shows the wreckage of the bus, taken in the aftermath, with the front clearly having suffered serious damage.

A person is seen being treated on the scene, but it is not known how seriously they were injured.

It has been widely shared online, and the horrific smash is thought to have happened in China.

At the start of the clip the driver is seen with one hand on the wheel as the man, wearing a light-coloured shirt, leaps up from his seat behind him.

Others tried to grab him when they realised what was happening, but it was too late.