Three people in Rotterdam were injured Saturday after police fired shots during a demonstration against COVID-19 restrictions. Several hundred rioters had descended on the Dutch city's shopping district late Friday in what Mayor Ahmed Aboutaleb called an “orgy of violence.”

Fifty-one people were arrested, half of whom were under 18, according to a Twitter post from Rotterdam police.

"We fired warning shots and there were also direct shots fired because the situation was life-threatening," police spokesperson Patricia Wessels told Reuters.

Police were instructed to use water cannons, and police on horseback were used to control the crowds of rioters. Aboutaleb said that "on a number of occasions the police felt it necessary to draw their weapons to defend themselves."

The city is under a state of emergency and closed down its public transportation.

The COVID lockdown restricts people from any indoor venues who do not have a “corona pass,” which proves a person has been vaccinated or proof of a negative Covid test. The firework ban was put in place to avoid “extra strain on healthcare,” according to their government.

Netherlands coronavirus cases and daily infections have been surging since the beginning of the pandemic. Officials put the lockdown in place to slow down cases.

People who recorded images or videos of the riots and shootings have been asked by authorities to send in footage for investigations.