Eight people were killed and 16 injured when a Delhi-bound bus rammed into a parked bus on Purvanchal Expressway in Barabanki on Monday, police said.
Prime Minister Narendra Modi expressed grief over the incident and said the state government is providing all possible help to the victims.
Superintendent of Police Anurag Vats said around 4.45 am, a private double-decker bus from Bihar's Muzaffarpur on its way to Delhi collided with another bus parked on Purvanchal Expressway under the Lonikatra police station area.
Additional Superintendent of Police (ASP) Manoj Pandey said the accident took place near an eatery close to Narendrapur Madraha village.
The parked bus was on its way to Delhi from Sitamarhi, also in Bihar. There were 36 passengers altogether in the two double-decker buses and police suspect the driver was sleepy at the time of 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 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.
Police took the injured to a community health centre in Haidergarh, from where those seriously hurt were referred to a trauma centre in Lucknow.
At present, nine injured are being treated at the Lucknow trauma centre and three at Ram Manohar Lohia Hospital on the state capital.
Other passengers were sent to their destinations after administering first aid.
Helpline 9454417464 has been issued in connection with the incident, the SP said.
The dead have been identified as Siddh Narayan Jha (75) of Phulparas, Shivdhari Sadam (42) of Madhubani, Om Prakash Rai (33) of Samastipur, Sapna Devi (33) Sitamarhi, Subodh (24) of Madhubani, Kamlesh Kumar (23) of Sitamarhi, Samsuddin (17) of Madhubani, and Aditya Kumar (12) of Sitamarhi.
Chief Minister Yogi Adityanath too expressed grief over the loss of lives and directed officials to ensure adequate treatment of the injured.