A man in his 60s was arrested by police on Saturday on suspicion of setting a Seoul subway train on fire, forcing hundreds of passengers to flee down a tunnel, according to authorities.

After entering the train with a gasoline bottle and a lighter-style torch, the suspect reportedly set fire to articles of clothing inside the Line No. 5 subway between Yeouinaru and Mapo stations at 8:47 a.m., according to witnesses and police, according to Yonhap news agency.

Twenty-one of the more than 400 passengers who managed to escape via the tunnel were hospitalized due to injuries such as broken ankles and smoke inhalation. There have been no reports of any significant injuries so far.

Before the fires were completely put out at about 10:24 a.m., passengers and the train conductor used fire extinguishers to confine them at first. 230 people, including police officers and firemen, were sent to the area by authorities.

After being on the run, the suspect was apprehended by police around 9:45 a.m. close to Yeouinaru Station.

After a period of suspension, subway service between Yeouido and Aeogae stations resumed at 10:06 a.m.

Police want to do a forensic analysis of the site and ask the suspect about the motivation.

Authorities are aggressively investigating the situation, and investigations are still under progress. We’re waiting for more information.