The accident occurred while passing through 2,556-meter Changwon First Tunnel on Namhae Expressway.

Two buses at the head of the line made it out of the tunnel unscathed however, five buses and four other vehicles collided in a chain reaction resulting in the complete crushing of a four-seat compact car that got sandwiched between two giant buses.

The police reported the vehicle had been pressed beyond recognition of the original shape. All four passengers died at the scene.

Surveillance camera recordings showed the cars tailgating without maintaining a safe distance.

The first bus crashed into a Sorento SUV, then a 5-ton truck hit the bus from behind. A second and third bus, then the compact car, followed by a fourth and fifth bus and a mid-sized SUV, were all unable to avoid the collision.

The cars after the SUV managed to swerve in time to avoid the other cars.

By Lim Jeong-yeo (kaylalim@heraldcorp.com)