The injured were taken to hospitals; at least three were in serious condition.

Videos of the incident were posted to social media and widely shared, depicting scenes of carnage and chaos in the square, which was crowded for an event. Several clips from national news networks showed the wounded and dead lying in the square, blood near their crumpled bodies. People ran to their aid, screaming and crying as they frantically sought to help.

In another clip, a crowd wrestles a man to the ground near a red Land Rover, its front end and bumper severely damaged, its windscreen smashed. The vehicle’s hazard lights are blinking.

One video, taken from above the square, showed dozens of people running from the area, screaming.