BEIJING (AP) — Authorities in southwest China say police suspect that a man who died in an explosion on a bus was responsible for igniting the fire that also injured dozens.

The Yibin city government in Sichuan province said on an official website Tuesday that a preliminary investigation by police shows that the blast on a public bus was caused by arson.

The fire broke out on Monday evening. Authorities have not said how many people were on the bus.

The government says a 51-year-old man named Yu Yuehai was suspected of committing arson. Yu was the only person who died in the blast.

Another 77 passengers and rescuers were sent to hospital for treatment or to be kept under observation, including 12 who were either seriously or critically injured.