Some 99 people were injured after four metrobuses collided in Istanbul’s Avcılar district on Friday.

Two metrobuses were involved in a head-on collision in the Avcılar stop, and two other incoming metrobuses crashed behind them, Anadolu Agency (AA) reported.

Ambulances, firefighters and police were dispatched to the area immediately after the crash. The injured passengers were taken to nearby public and private hospitals for treatment, the report said.

The metrobus traffıc on both ways was halted following the accident, which led to heavy traffic on the D-100 highway, as passengers tried to walk to reach other means of transportation.

Metrobus, an exclusive-lane bus, was introduced to the city in 2007. Since then, several accidents have taken place on the 50-kilometer-long route spanning from Beylikdüzü district on the European side to Söğütlüçeşme on the Asian side, but few were fatal. In 2015, five people were killed when a car plowed through the barriers separating the metrobus lane and crashed head-on with a metrobus. Metrobuses were also subject to fires.

Metrobuses, mostly overcrowded during rush hours, carry thousands of passengers every day and they were less crowded during the pandemic when restrictions reduced the number of commuters. With the start of a normalization process – where curfews and most restrictions related to the pandemic were lifted on July 1 – they are again brimming with passengers, especially in morning and evening rush hours in the city of more than 15 million people.