Updated

China's state broadcaster says that nine people have been killed in a gas explosion at an underground mine. Eleven other people are trapped in the coal mine in northwest China.

State broadcaster China Central Television says the explosion happened Tuesday morning at a mine in the Shizuishan city area of Ningxia Hui Autonomous Region.

It says rescuers are trying to reach the trapped and that the cause of the explosion is being investigated.

An officer at the Shizuishan city government confirmed the gas explosion, but said he had no details.

China's mines have long been the world's deadliest, but safety improvements have reduced deaths in recent years.