Eight people were killed and 16 injured when a Delhi-bound bus rammed into a parked bus on the Purvanchal Expressway here on Monday, police said.

Prime Minister Narendra Modi expressed grief and said the state government is providing all possible help to the victims.

Both the double-decker buses were plying from Bihar to the national capital, they said, adding there were 36 passengers altogether during the accident.

"The accident on Purvanchal Expressway in Barabanki is extremely saddening. I express my condolences to those who have lost their loved ones. Along with this, I wish speedy recovery to all the injured. Under the supervision of the state government, the local administration is engaged in providing all possible help," Modi was quoted as saying in a tweet by his office.

Additional Superintendent of Police (ASP) of Barabanki Manoj Pandey said the bus travelling from Sitamarhi rammed into the other bus which was halted at a roadside eatery near Narendrapur Madraha village in Loni Katra police station area.

The accident took place at around 4.30 am. Police suspect the driver was sleepy.

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

Police took the injured passengers to the community health centre in Haidergarh, from where those seriously injured were referred to the trauma centre in Lucknow.

Chief Minister Yogi Adityanath too expressed grief over the loss of lives and directed officials to ensure adequate treatment of the injured.