It was not immediately clear what caused the blast which took place in the residential building in Premia de Mar, a resort town some 25 kilometres (15 miles) north of Barcelona.
"The explosion happened at 8:25 am, injuring 17 and killing one person," a spokeswoman for Barcelona's fire brigade told AFP.
Local media showed images of a fire burning in a seven-storey building, saying the structure had been evacuated while investigators tried to determine what caused the blast.
Catalonia's Minister of Home Affair Jordi Jané said that a team of firefighters and police were still examining whether Sunday's explosion was “accidental or not”, according to Europa Press.
Town mayor Miquel Buch told reporters on Sunday that when an explosion of such magnitude occurs, officials must check “if it was an accident, or had a criminal origin”.
Officials also told reporters that there seemed to be indicators that it was a gas explosion.
The woman who died was between 50 and 60 years old, and was living on the floor where the explosion originated.
Of the 17 injured, Europa Press reports that the most severely wounded person was a man living in the building who sustained burns over 30 percent of his body and is in hospital in serious condition.
Two others were sent to intensive care in stable but serious condition, while third person who was not living in the building was taken to hospital due to respiratory problems caused by the blast.
Dozens also have been left homeless by the explosion in the building where it happened as well as those next to it.