The vehicles, after the collision, fell 15-metre down from the Sindhupalchok-Bandeu-Chautara road, killing two persons, police said.
The injured passengers were rescued immediately after the accident.
Those critically injured were referred to a hospital, the district police office said.
"The other passengers who suffered minor injuries have been taken to the district hospital," the police said.
Meanwhile, a boy was killed and two other persons went missing following a landslide triggered by continuous rainfall at Rajwara in Pyuthan yesterday.
In a separate incident, three persons went missing after a landslide swept away their house at Hosrangdi of Mahashila Rural Municipality.