Thirteen people have been reported dead in the twin explosions that rocked Urumchi, northwest China's Xinjiang Uygur Autonomous Region, on Thursday.

Eighteen are reported injured in the explosions in Muslim-dominated Urumchi as the people celebrated Eid.

Head of the public security department of Xinjiang, Liu Yaohua, said the investigations revealed that the bombs were manmade, indicating that it could be a terrorist strike.

The kind of explosives used and other details are not yet known, he added.

The first blast occurred at around 1200 IST in a minibus travelling from the Dushanzi district of Karamay city to Usu city in northern Xinjiang.

Nine passengers were killed on the spot, two others were declared dead on reaching hospital.

Two of the injured are in critical condition and five others have received medical assistance.

Four hours later, a natural gas leak caused a blast, which killed two people and injured 11, in Urumchi.

The blast left a nine square meter hole in the ground, official sources said.