At least four medical students were killed and 31 injured when a bus carrying them overturned after hitting a roadside tree at Gollapudi near Vijayawada late Monday night, police said.The driver of the private bus was also killed in the accident which occurred on Vijayawada-Hyderabad highway.The students of government-run Osmania Medical College were returning to Hyderabad after participating in a sports tournament in Andhra Pradesh when the accident occurred.Police said the driver was drunk and driving the bus at a high speed, which led to the disaster. The survivors said the driver picked up an argument with them when they raised an objection to driving in an inebriated condition.MBBS fourth year student P. Rajaram, House Surgeons Giri Lakshman and M. Vijay Teja and driver died on the spot. Another student succumbed at a hospital at Gollapudi.The injured were admitted to the hospital, where condition of some of them is stated to be critical.Telangana Health Minister Lakshma Reddy rushed to Vijayawada from Hyderabad. He called on the injured at Andhra Hospital in Gollapudi. The minister said Telangana government will bear all expenses for the treatment of the injured.The minister said action would be taken against those whose negligence led to the accident.Telangana Chief Minister K. Chandrasekhar Rao expressed shock over the death of the students. He directed officials to ensure best possible treatment to the injured and if necessary shift them to Hyderabad.