The accident occurred early on Thursday, when the truck, carrying pilgrims from a shrine in Himachal Pradesh back to Punjab, rolled down near Manguwal barrier, 20 km from Hoshiarpur. The accident site is 175 km from Chandigarh.
Hoshiarpur district police chief Sukhchain Singh Gill confirmed that 20 people died in the accident. Police said 14 died on the spot.
Those injured in the accident were taken to hospitals in Hoshiarpur.
Police said that the truck driver failed to negotiate a sharp curve on the hilly road near the Punjab-Himachal Pradesh border, and the truck went off the road.
Most of the victims, who were from Bholath area of Kapurthala district, were asleep when the accident occurred. Rescue efforts were hampered since the accident occurred in hilly terrain before daylight.