The remains of one of the girls were found in the aftermath of the blaze.
By the time emergency services arrived at the scene the fire was already out of control.
The girls’ mother, her boyfriend and his 19-year-old son were all on the ground floor when the fire broke out and were all able to escape. One of them received burns while trying to go upstairs to rescue the girls.
All three were taken to Ljungby Hospital to be treated for minor injuries.
“We asked them some preliminary questions during the night. When they realized something was burning, there was already a full-blown fire on the upstairs level,” said police spokesman Robert Loeffel.
Despite the efforts of thirteen firemen, nothing could be done to save the girls’ lives.
“Firemen equipped with smoke helmets tried to go in but it was impossible,” said fire services spokesman Mikael Jönsson.
The cause of the fire is not yet know. Police forensic experts were brought in to scour the area on Thursday. All that was left of the house were the outer walls.
Police said they did not have any suspicions of foul play.
According to Ulf Erlandsson, a fire investigator at the Swedish Rescue Services Agency, it is unusual for young people to perish in fires in Sweden.
“It is most common for people who are old, senile, sick or disabled to die in fires,” he said.
Last year, a total of 95 people died in 81 different fires, according to the agency’s preliminary statistics.