Rioting broke out in the Dutch city of Rotterdam as hundreds protested against new COVID-19 restrictions.
Some heaved objects at police.
In response, authorities used water cannons and charged their vehicles into protesters.
Dutch police fired warning shots and injured several people, though none of the injuries were life-threatening.
Video on social media showed burnt out police cars and fire crews putting out flames.
Crowds were angry at authorities planning to introduce a new law.
It restricts access to bars, restaurants and sports matches to those who have a pass to prove they've been vaccinated, have recovered from an infection, or tested negative for the coronavirus.
The Netherlands re-imposed some lockdown measures last weekend for an initial three weeks to slow an upswing of COVID-19 infections.
The country recorded over 20,000 new daily cases for several days in a row this week, a record high since last December.