Canadian Liberal Prime Minister Justin Trudeau was hit by a handful of gravel on Monday, television images show, as he made his way to his campaign bus past a crowd shouting their opposition to Covid-19 vaccines.

A CTV camera captured what looks to be white gravel hitting Trudeau and one of his bodyguards as he walked toward his campaign bus in London, Ontario. The Liberals cancelled an event late last month because of safety concerns linked to anti-vaccine protesters.

Trudeau played down the incident on his plane later, saying he may have been hit on the shoulder, and once he had pumpkin seeds thrown at him, according to a video posted on Twitter by Global News TV reporter Abigail Bimman.

Earlier on Monday, Trudeau assailed Conservative leader Erin O’Toole’s opposition to vaccine mandates and called the hecklers “angry mobs” of anti-vaxxers.