A truck carrying Nepali villagers and wildlife park employees ran over a landmine planted by Maoist rebels on Tuesday, killing 11 people, officials said.
The blast occurred near the Royal Shuklaphanta Wildlife Reserve in Kanchenpur district, about 600 km (375 miles) west of the capital, district administrator Dhurba Raj Wagle said.
"There was a huge explosion and metal strips from the truck were seen hanging from nearby trees," an army officer told Reuters. Four people in the truck were wounded, he added.
It was not clear if the mine was intended for the truck or vehicles used by security forces who guard the park.
The Maoists have been fighting since 1996 to topple the monarchy and set up a communist republic in the world's only Hindu kingdom, wedged between China and India.
The revolt has claimed more than 9,000 lives so far - 1,800 of them since August when the guerrillas pulled out of peace talks and broke a seven-month truce.