The six doctors were travelling in a Toyota Innova SUV on the six-lane expressway where speed limit is set at 100 kilometres per hour.
Police said the Innova tried to overtake the Eicher mini-truck around 2:30 am when it lost control and hit the larger vehicle from behind. It is yet to be determined at what speed the SUV was trying to overtake the mini-truck. The mangled steel door of the SUV came off its hinges and was seen lying on the expressway, suggesting a very high impact speed.
The accident happened near Mathura, 60 kilometres from Agra, where the 165-km-long expressway ends.
Three of the AIIMS doctors who died on the spot have been identified as Dr Hem Bala, Dr Yashpreet and Dr Harshad. Four others -- Dr Catherine, Dr Abhinav, Dr Mahesh and the driver whose name is not known yet -- have been taken to AIIMS in Delhi for treatment.