A huge explosion at a house more than 120 miles from Barcelona is now being linked with the van rampage that left 13 people dead and 100 injured and a second attack in Cambrils.
Spanish police initially blamed the blast in the town of Alcanar, in Catalonia, which completely destroyed the property, on a gas explosion.
But officials said police were working on the theory that the Cambrils and Barcelona attacks were connected, as well as Wednesday's explosion in Alcanar.
One person was killed in Wednesday’s blast and six were injured.
The body of a woman was discovered among rubble along with a man who was taken to hospital in a critical condition, police said.
At a press conference on Thursday, Josep Lluis Trapero, head of the Mossos police, told reporters that they believed there is a connection between the occupants of the house and the perpetrators of the Barcelona attack.
Dramatic images showed the house completely destroyed following the blast.
Detectives discovered 20 canisters of propane and butane in the ruins of the building.
Neighbours described hearing a “huge boom”.
Ellaine Fernandez told Spanish newspaper El Pais: “"I was having dinner with some friends when we felt a massive boom - the lights went out and the windows shattered.
"I called out for my husband, who was injured in the head and taken to hospital, and a cousin was also injured.
"The rest had cuts, light injuries."
It is believed the house had been occupied for just a few months before the blast.
Catalonian officials confirmed 13 people were killed and 100 injured after attackers ploughed a van into crowds at Las Ramblas in Barcelona on Thursday afternoon.
A white van mounted the pavement and veered into crowds at the tourist hotspot around 5pm (local time).
Seven people, including a police officer, were injured after the suspects rammed a car into crowds during the carnage in the coastal town.
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