People in Barcelona have gathered at the site of Thursday’s van attack, lighting candles and writing messages in tribute to the victims.
One woman sang a rendition of John Lennon’s song ‘Imagine’.
At least 13 people were killed and more than 100 injured on the popular Las Ramblas avenue.
Spanish police say that the driver of the van that ploughed into crowds may still be alive and at large.
They initially believed he was Mousa Oukabir, one of the five men shot dead by police in the Catalan resort of Cambrils, 120 km down the coast from Barcelona, after they drove their car at pedestrians and police officers.
But now they say the driver could have been Younes Abouyaaqoub.
The driver abandoned the van and fled on Thursday after speeding along a section of Las Ramblas, the most famous boulevard in Barcelona, leaving a trail of dead and injured among the crowds of tourists and local residents thronging the street.
Police have arrested four people in connection with the attacks – three Moroccans and a citizen of Spain’s North African enclave of Melilla. They were aged between 21 and 34, and none had a history of terrorism-related activities.
Another three people have been identified but are still at large. Police in France are looking for the driver of a white Renault Kangoo van that may have been used by people involved in the Barcelona attack.
Authorities have issued arrest warrants for four further suspects in connection with the two attacks.