Fireworks were accidentally set off as they were being set up for an Independence Day show in Ocean City, Maryland, leaving employees of the pyrotechnics company with minor injuries, authorities said on Sunday. A few hours after the blast, the city said the day’s fireworks shows in several locations had been cancelled through caution. The Ocean City Fire Department said it was alerted to a vehicle fire on Sunday morning and found that the fireworks that had gone off at the beach. An undisclosed number of employees had minor injuries but declined be taken to a hospital, the department said. Videos of the explosion posted to social media show the fireworks popping and crackling near a crowded beach. A safe zone around the fireworks area prevented any people at the beach or boardwalk from being injured, the fire department said. The city said on Sunday afternoon in announcing the fireworks cancellations that the cause of the explosion was unknown. “A perimeter around the fireworks site has been established and will remain in place until the safety inspections are complete, which could take several days,” the news release said.