The incident occurred on the Badaun-Panipat road last night when the victims were going to attend the Ganga Snan Mela at Tigree area of the district, they said.
The injured were admitted to a local hospital, from where two persons with serious injuries were referred to Meerut, an official said, adding that police is probing how the trailer entered on the road that was closed for heavy vehicles.
A manhunt has been launched to nab the absconding trailer driver, he added.
