China's state news agency says a head-on collision between a truck and a tour bus outside Shanghai has killed at least 13 people and injured many more.

Many of the dead in Sunday morning's accident were tourists on their way from the eastern financial center to the city of Changshou to view blooming peony flowers.

The Xinhua News Agency said the cause of the accident was under investigation and local police and government officials said they had no additional information. The Shanghai Daily newspaper reported online that the cause might have been a blown tire.