The deceased are Narayan Khadka, 50, and Som Bahadur Tamang, 16, of Dhorthali-4, according to District Police Office.
The injured are being treated at Sadabahar Hospital in Khadichaur.
Madhes-based leader Rajendra Mahato's newly formed political party, Rastriya Mukti Party Nepal, has been officially registered with the Election Commission (EC).