"Three rioters were injured when they were hit by a bullet. They are still at the hospital," the Rotterdam police said in a Saturday statement.

According to the release, one police officer was hospitalized with an injury to his leg and another one was treated on site by paramedics.

"Numerous police officers suffered minor injuries and hearing damage," the police said, explaining that officers were attacked with stones and fireworks.

Rotterdam police said that 51 people were arrested during the unrest on Friday evening and night; half of them were underage.

The Rotterdam rally began on Friday against new coronavirus restrictions announced last week. In the evening, police used water cannons and fired warning shots to disperse the crowd. Local media reported that at least 20 protesters were arrested and at least seven people, including police officers, were injured during the clashes.

Last week, the Dutch authorities said that a new set of restrictive measures aimed at preventing the spread of COVID-19 were coming into effect until December 4. The restrictions obligate essential shops and supermarkets as well as drugstores, restaurants, cafes, and bars to close at 8 p.m. Other shops, hairdressing and beauty salons should close at 6 p.m. Sporting events should be held without spectators, but the restrictions do not affect concert halls, movies, and theaters. Social distancing of 1.5 meters (5 feet) was reimposed and people were recommended to work from home.