Eight passengers died and 20 were injured in a collision of two double-decker buses on the Purvanchal Expressway near Uttar Pradesh’s Barabanki on Monday, ANI reported.

The accident took place at around 4.30 am.

Three passengers have suffered serious injuries and have been referred to the trauma centre of King George Medical University in Lucknow.

Additional Superintendent of Police Manoj Pandey said the accident took place when a bus coming from Sitamarhi in Bihar hit a stationary bus from behind, according to PTI. The police suspect the driver was sleepy.

Four of those killed have been identified as Om Prakash Rai (33) of Samastipur, Shivdhari (42) of Madhubani, Chitnarayan (75) of Madhubani and Kamlesh Kumar (23) of Sitamarhi in Bihar.

Uttar Pradesh Chief Minister Adityanath expressed grief over the accident and directed officials to conduct relief and rescue work expeditiously.

Prime Minister Narendra Modi also offered his condolences to the families of the deceased.

“The accident on Purvanchal Expressway in Barabanki is extremely sad,” the prime minister said. “I wish speedy recovery of the injured. Under the supervision of the state government, the local administration is engaged in all possible help.”