The suspect behind Friday’s Hong Kong MTR attack, identified as Cheung Kam-fai, has been charged with arson, after 19 people were injured.

Cheung, a 60-year-old man with a history of mental illness, ignited a bottle of flammable liquid on a MTR train when it arrived at Tsim Sha Tsui station at around 7 p.m. on Friday. 

The incident injured 19 people, while three peop‍le remain in a critical condition with serious burns. 

Tsim Sha Tsui station on the Tsuen Wan Line, one of the city’s busiest interchanges, was forced to close during the evening rush hour after the train fire.

Local authorities confirmed that Cheung was diagnosed with delusional disorder in 2007 after committing an act of violence, and he had missed his medical appointment on the day of the attack. The police contacted Cheung’s family as part of an investigation, and finished searching for evidence on Saturday. 

Cheung is not expected to appear in Kowloon City Court in person when the case is mentioned on Monday, South China Morning Post said, citing police.

The arson attack has sparked concern over the security of Hong Kong’s metro system. Nearly five million passengers take the metro in Hong Kong every day, however, nearly half of trains do not have closed-circuit television security cameras. 

Operations director of Mass Transit Railway (MTR) Adi Lau admitted that the train involved did not install CCTV cameras, according to a report by South China Morning Post. He also said new batches of CCTV-equipped trains would come into service by 2018 at the earliest.   

An initial report on the incident is expected to be submitted one month later.