AMSTERDAM—Five police officers were injured in the Netherlands and at least 28 people detained across three provinces as violent protests against COVID-19 restrictions continued for a second night into Sunday. Dutch authorities used water canon, dogs, and mounted police to stop rioting youths who set fires and threw fireworks in the worst disturbances since a full lockdown led to widespread disorder and more than 500 arrests in January. The latest unrest began on Friday night in Rotterdam, where police opened fire on a crowd that had swelled to hundreds during a protest the city’s mayor said had turned into “an orgy of violence.” Three people believed to be hit by police bullets remained in hospital on Sunday, a statement by the authorities said. The protests were sparked by opposition to government plans to restrict the use of a national corona pass to people who have either recovered from COVID-19 or …