A manhunt was underway for the driver of a van that mowed through crowds of tourists on Barcelona's most famous avenue on Thursday, killing at least 13 people in an attack that was claimed by Islamic State.
Authorities said the death toll could rise, with more than 100 people injured, some seriously.
Police said they arrested two men, a Moroccan and a man from Spain's north African enclave of Melilla, though neither was the driver. Witnesses said the driver fled on foot.