At least nine people were killed and four others were injured when a car struck pedestrians near Seoul city hall on Monday, police said.

There were six fatalities at the scene, while three others were pronounced dead after being rushed to hospital, firefighter Kim Chun-soo said.

South Korea’s Yonhap news agency reported that a 68-year-old driver crashed into people who were waiting at a traffic signal. He was driving in the wrong direction and hit two other vehicles before ploughing into the pedestrians, Yonhap said.

A man was detained by police over the incident, said Kim Suk-hwan, safety and transport director at the city’s Jung-gu district office. Investigations are underway to determine if drugs or alcohol were involved, as well as whether the deadly incident was caused by accidental acceleration, Kim said.

Seoul Mayor Oh Se-hoon described “a very sad accident” as he visited the crash site, according to city authorities. He also ordered officials to “take the victims to the hospital quickly and thoroughly identify the cause of the accident”. Deadly transport accidents with multiple casualties are rare in South Korea, which generally has well-maintained roads and vehicles.