After having dinner at Moga, the youths left for Nahal Khote and when their car reached Singhanwala village last night, it rammed into the truck loaded with sand, they said.
The youths might not have seen the truck because of very low visibility caused by thick fog, police said.
Three of them died on the spot while the fourth one succumbed to his injuries while being taken to civil hospital, they said, adding the deceased have been identified as Hussandeep Singh, Swaran Singh, Sukhdev Singh and Sukhpreet Singh.