Here is what we know so far about the terror attack.
When what and where the attack happened
The attack took place on Thursday at around 5 pm local time when a white van crashed into a busy street in Barcelona's Las Ramblas, a destination popular with tourists, for 500 meters. The attack killed at least 13 people, while several others were left injured.
According to Spanish media, three Germans and one Belgian were among the 13 who were killed in the attack.
Witnesses account
Eyewitnesses and survivors called the terror attack "horrific" and said the victims were "screaming in terror" and "flying into the air," according to CNN. Ali Shirazinia, an eyewitness, said he heard screams when he was riding his bike.
"I looked over to my left and I saw all of the people along the promenade kind of split into two -- some going right, the rest coming really towards me, screaming and running as fast as they could," he said, adding, "I saw people flying into the air and everybody was kind of running into the shops on either side of the Ramblas, and a lot of people were in shock."
Another eyewitness, Lourdes Porcar, told TV3 television station that the van was crashed into the street without caring about the people. "It was going very fast, without caring about who was in its way," she said.
Tourist Susan McClean told CNN that children were screaming and people were running. "You could see the fear and the distress in these people, and the fact that they were screaming in terror. Regardless of what might have happened we knew we had to get ourselves out of there," she said.
After Ramblas, two other attacks took place at Alcanar and Cambrils. On Wednesday, two deadly explosions at a house in Alcanar killed at least one and injured 16 others.
Hours after Ramblas attack, another terror attack took place in Cambrils, a coastal town located around 120 km from Barcelona. The attackers were in an Audi A3. "The alleged terrorists were in an Audi A3 and apparently knocked down several people before coming across a police patrol and a shoot-out ensued," The Telegraph quoted a spokesman for the regional government of Catalonia as saying.
Catalan police and the region's interior minister, Joaquim Forn, have confirmed that the house explosion in Alcanar and the attack in Cambrils are linked.
Two people – one born in Morocco and another in the Spanish enclave of Melilla – have been arrested in connection with the Ramblas attack, but neither of them was the driver. The Morocco born suspect, identified as Driss Oukabir, pleaded innocence and said that his documents were stolen.
In connection with the Cambrils attack, police shot dead five attackers, who appeared to be wearing explosive belts. The bomb squad later detonated the explosive belts, reports suggest.
The Islamic State of Iraq and Syria, also called the Islamic State of Iraq and the Levant (ISIL), claimed responsibility for the Ramblas attack. "The executors of the Barcelona attack were soldiers of the Islamic State," the jihadist organisation's propaganda outlet Amaq said on its Telegram messenger account.
