SEOUL, Oct. 14 (Xinhua) -- Ten people were killed and seven others injured as a tour bus caught fire near South Korea's southeastern city of Ulsan, local media reported on Friday.

The bus carrying a group of retired employees of a local chemical company was engulfed in flames at about 10:11 p.m. local time on Thursday (1311 GMT) on a highway near Ulsan.

Among the 20 people aboard, 10 managed to escape by breaking the windows with emergency hammers and jumping out, but the others were killed inside as the bus door was blocked against the guardrail.

Seven escapees were injured who were taken to a nearby hospital. One was reported to have suffered injury while helping rescue the passengers.

All of the passengers are retired employees of Hanwha Chemical and their spouses in their mid-50s up to early 70s. They were heading back to Ulsan after returning from a group trip to China.

A preliminary investigation by police and firefighting authorities said a sudden rupture of the right front tire had led the bus to tilt rightward.

The bus was presumed to have skidded about 200 meters along a guardrail, and the fractional heat caused the blaze. More detailed investigation was underway.