The driver of the tour bus in which 26 people died when it crashed into a barrier and caught on fire in Taiwan on July 19 was drunk when the accident occurred, investigators said on Friday.

In the worst road accident ever to overcome Chinese mainland visitors to the island, the entire tour group of 23 tourists and a guide were killed as they headed for Taiwan Taoyuan International Airport to return home. The driver and another tour guide from Taiwan also died in the crash.

Investigators said tests done on the driver, identified only by his surname Su, revealed his blood-alcohol level was 215 mg per 100 ml, more than four times the legal limit.