A horrifying video has gone viral online, showing the moment a BMW driving at "lightning speed" crashes into a Mazda sedan in China, smashing the vehicle into pieces.

The incident, captured by surveillance cameras, happened last Saturday in Nanjing.

Both passengers in the Mazda were thrown out of the car and reportedly pronounced dead at the scene.

According to ET Today, the BMW was going at least 150kmh when it ran a stop light and struck the oncoming Mazda at the intersection of Shiyang Road and Youyihe Road in Qinhuai District.

Pieces of the completely destroyed Mazda flew for several metres, hitting a public bus and a taxi.

Said a witness surnamed Zhao: "I just felt a gush of wind and a strong vibration at the left-hand side of my car. Then I heard a loud noise and saw a car thrown into the air."

The 35-year-old BMW driver, who is said to have abandoned his car immediately after the accident, was arrested some 300m to 400m away from the scene, with his face covered in blood.

According to shanghaiist.com, police confirmed that the driver tested negative for drugs and alcohol, and released DNA tests showing that the suspect's blood type was identical to samples found in the BMW.

The arrested man has been detained as police investigate the situation.