A bus triggered a crash involving dozens of passenger cars, a truck, and four other buses in Seongnam, South Korea on Wednesday morning, leaving many injured, according to South Korean authorities. 

What do we know so far?

The fire department of Gyeonggi Province, were Seongnam is located, said 57 people were injured, with nine seriously hurt after the bus initiated a crash involving 32 vehicles and then slammed into a median strip. None of the injured were in life-threatening condition. Yonhap News Agency had reported that 48 people were injured and six of them had serious injuries. 

An investigation has been launched into the cause of the collision. 

The driver told investigators the brakes on his bus had failed, according to a report by Yonhap news agency. The man, believed to be in his 60s, tested negative in a breathalyzer test. Local media had reported that he was also hospitalized after the crash. 

The city of Seongnam, with its population of nearly 900,000, is located just south of the capital metropolis of Seoul. The crash occurred during rush hour traffic.

Dozens of fire personnel and vehicles were deployed to the scene of the crash and a emergency medical station was also set up there.