The accident happened when the bus, carrying 25 people, and the car crashed into each other on the E4 motorway between the towns of Piteå and Luleå.
Two adults and one child travelling in the car died from the injuries they sustained in the crash, Norrbotten county police said in a statement.
Two other children travelling in the car were also injured — one of them seriously — and 15 people travelling in the bus were injured, the statement added.
The bus skidded off the highway and fell on its side in a ditch.
A sports club from the town of Skellefteå said on its website its men’s football team was travelling in the bus to a game in Luleå.
While some of the players were trapped in the bus when it overturned, all the players were rescued and only three were still in the hospital, it added.