SEOUL, South Korea — A driver whose car struck pedestrians waiting at a crowded intersection in South Korea’s capital, killing nine people, will be investigated on allegations of accidental homicide, police said Tuesday.

The car hit several people Monday night in central Seoul, after reportedly going in the wrong direction and colliding with two other cars. Six other people were injured, including the driver who was detained.

The driver told investigators that his car accelerated abruptly and unintentionally. Police said his car would be sent to the country’s forensic agency for an examination.

Police said Tuesday that tests showed the driver was not under the influence of alcohol or drugs. They will consider seeking a formal arrest warrant to extend his detention if it is needed for an investigation.

Police declined to disclose the identity of the driver, citing privacy regulations, but South Korean media reported that he was a bus driver in his late 60s from Ansan, a city just south of Seoul, who has 40 years of driving experience.