JINAN - Twelve people, including 11 kindergarteners, were killed Tuesday when a school bus crashed and then burst into flames as it traveled through a tunnel in East China's Shandong province.

Of the 11 children, who were aged between three and six, five were Republic of Korea (ROK) nationals and six Chinese nationals. They were all students at an international kindergarten in Weihai City, local authorities said.

The accident occurred at about 8:59 a.m. inside Taojiakuang tunnel in Huancui District when the rented bus was on its way to the kindergarten with 13 people onboard, including the children's teacher.

The driver also died and the teacher has sustained serious injuries. Both the driver and 11 children's identities have been confirmed via DNA identification, according to Ye Liyun, a deputy mayor of Weihai.

The provincial government has assigned a team, headed by a vice provincial governor, to investigate the accident.

"An initial investigation shows this traffic accident was caused by a rear-end collision," said Ye.

Weihai Municipal Hospital has opened an emergency "green channel" to treat the injured teacher, who is conscious with stable vital signs.

Weihai municipal goverment has set up 13 teams for relief works. Korean interpretors have also arrived at the scene to assist with follow-up works.

The kindergarten is part of an international school that was set up in 2006 to accommodate children of ROK business people in Weihai, according to records of China's education ministry.