At least 39 people were injured in a petrol bomb attack on a bank in northwest China's Gansu Province, state news agency Xinhua said on Friday. The explosion happened in Wuwei city in Tianzhu Tibetan Autonomous County. Witnesses quoted by Xinhua said the bomb was thrown at 08:30 local time (0030 GMT) while staff were having a meeting and that a number of people then threw themselves from a fourth storey window. More were carried out on stretchers, the witness sad. The Tianzhu government website said that a former Han Chinese employee dismissed recently for embezzlement had carried out the attack. "He committed arson to take revenge," a statement said.