Thirteen persons were killed and at least four injured when a truck rammed into a bus near Sirohi in southern Rajasthan early on Thursday morning, police said."The incident occurred in the morning today (Thursday) near Paldi M Village in Sirohi district when a speeding truck-trailer hit a parked bus. The collision was so strong that the bus overturned and fell on some of the passengers standing near it. At least nine people lost their lives on the spot while four died later," a police official told IANS.He said that four persons who were seriously injured have been referred to a hospital in Udaipur. "Prima facie it looks like a case of speeding and negligent driving. But we can only arrive at a definite conclusion after detailed investigation," the police official said.The state government has announced compensation of Rs 50,000 each for the next of kin of the deceased, Rs 5,000-10,000 each for the injured.