BRUSSELS – Spain came under repeated attack starting Thursday in what authorities called linked terrorist incidents, when a driver swerved a van into crowds in Barcelona’s historic Las Ramblas district, killing more than a dozen people and injuring scores of others. Early Friday, an attempted attack unfolded in a town down the coast. The Islamic State claimed responsibility for the Barcelona violence.

The initial attack broke the peace of a warm summer afternoon in a packed, tourist-friendly area of Barcelona at the peak of vacation season, and the victims came from well beyond the city’s borders. Authorities said that 15 people had suffered serious injuries and that the death toll could rise. More than 100 people were hurt, said Joaquim Forn, the interior minister of the Catalan regional government.