ATHENS — A peaceful demonstration by tens of thousands of people in Athens turned violent on Sunday, as protesters seeking to enter the Parliament building used clubs, firebombs and other objects to attack officers guarding the building, according to the police.

For the most part, the rally, called days before the Greek Parliament was to vote on ratifying an agreement to rename the country’s northern neighbor North Macedonia, was peaceful. But around 3 p.m., clashes broke out and footage shared on social media showed the police using tear gas on some demonstrators. The police said that 25 officers had been wounded in the clashes and that seven people had been arrested.

The office of Prime Minister Alexis Tsipras accused extremists of trying to force their way into Parliament and of attacking police officers with stones and clubs, wounding dozens of people. A photographer was among those injured.