In the incident that occurred late last night, the van, in which a family from Barabanki district was returning after a religious ceremony, collided head-on with the bus, said B Yadav, in-charge of Inhauna police outpost.
Mamta Vaishya, Reena Vaishya and Satyam (12) were killed in the mishap, while five persons of the same family were rushed to Trauma Centre Lucknow in serious condition, Yadav said.
The bus was seized and its driver was arrested, the in- charge added.