Authorities are calling it a terror attack.
NBC News reports authorities are looking for at least one suspect in the popular tourist district, Las Ramblas.
British tourist Steve Garrett said he watched the scene unfold, with waves of screaming people–many tourists–rushing into the market area. Then the police came.
“They looked like they were sweeping the market area, it was quite clear they were looking for somebody or something,” Garrett said.
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