According to local reports, one man aged 30-35 died, along with another man aged 40-45, a woman aged 40-45 and a girl and a boy, both under the age of 15.
In the accident, in which two cars apparently collided head-on, another young girl was badly injured. She has been taken to a different hospital.
The emergency services were alerted to the incident at 1.20pm.
“In one car were two adults and three children. In the second car a single person was travelling alone,” said Stig Olson of the Ljusdal emergency services.
The car carrying the family caught fire after the collision, but other motorists were able to put out the flames quickly.
“The driver in the other car was trapped,” said Olson.
The cause of the accident, which occurred on a straight stretch of road, is not yet clear. Driving conditions on the road were good at the time of the crash.
The people involved in the accident were not residents of Gävleborg district.
Good Friday is one of the most dangerous days of the year on roads in Sweden, according to statistics from the Swedish Roads Administration.