According to local authorities, five other people were injured in the fire, one of whom is in a serious condition.
Firemen managed to put out the flames less than an hour after it began, Spanish daily ABC reported on Wednesday.
All the victims were living in a 60 sqm flat in the town of El Vendrell, in the northern Spanish province of Tarragona.
“We managed to save the mother and one of the children, but couldn’t do anything for those who lost their lives,” the head of Tarragona’s fire squad told ABC.
All other residents in the building were able to escape without difficulty as the fire occurred on the top floor.
A team of psychologists was also called to the scene of the tragedy to aid the survivors.