At least 18 people were killed and 19 others injured after the double-decker bus - they were travelling in - collided with a milk tanker in Uttar Pradesh's Unnao on Wednesday.
Three women and one child were among those killed in the accident, the police said.
The bus was travelling from Bihar's Sitamarhi to Delhi when it rammed the tanker from the behind on the Lucknow-Agra expressway near Garha village.
The force of the impact was such that the bus was pulverised and people were flung out of the vehicle, the police said.
Visuals from the scene showed bodies on the ground, twisted scraps of metal, shattered glass and debris of destroyed belongings.
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"Today at around 5:15 am, a private bus coming from Motihari, Bihar, collided with a milk tanker. Eighteen people have lost their lives, and 19 others are injured in the accident, said Gaurang Rathi, District Magistrate, Unnao.
The cause of the crash is under investigation. Initial probe suggests the bus was overspeeding, Rathi said.
The injured have been rushed to a hospital for medical treatment.
Chief Minister Yogi Adityanath has expressed anguish over the tragedy and directed the officials to ensure proper treatment of the injured, his office said.
