The fires broke out on Sunday, affecting the Costa Brava, one of the country's most popular beach destinations, as well as major motorways used by holidaymakers driving to and from southern France. Ash from the blaze has also begun to reach the Barcelona area.
The fires in the Spanish province of Girona, Catalonia, are the area's most devastating in well over 20 years, the local government said, and Environment Ministry data show 2012 is already the worst year for forest fires in Spain for more than a decade.
All four victims were French, the government of Catalonia and the fire service said. The fourth victim was a 64-year-old man who died of burns yesterday.
On Sunday, a father and his 15-year-old daughter died after trying to escape the flames by descending a cliffside in Portbou, a coastal town where one of the fires broke out. A man died of a heart attack further inland near La Junquera, a border town at the epicentre of the biggest blaze.
The Catalan government said at least 23 people had been injured.