A Chinese tour bus plunged off a cliff in Tibet early Wednesday, killing 11 people, state media reported.

The accident took in Gonggar county just south of the regional capital of Lhasa, where the city's airport and many of Tibet's most famous tourist attractions are located, the official Xinhua News Agency reported.

It said eight other people were injured in the accident, and that the cause was under investigation.

Xinhua said the bus belonged to a Lhasa-based tour bus company, but gave no details about those on board.

While foreign visitors to Tibet are tightly restricted, the Himalayan region has grown increasingly popular with domestic Chinese tourists drawn to its striking mountain vistas and traditional Buddhist culture.

Visitor numbers hit 15 million in 2014, up more than 20 percent from the year before, bringing in close to $2 billion in revenue, according to official figures.

Despite the opening of a high-altitude rail line from inland China to Lhasa, infrastructure in much of the vast area is still primitive and many cliff-side roads are narrow and unpaved.