Dressed in traditional costume, revellers - known as Caretos - have been racing through the streets of the Portuguese village of Podence in a ceremony that was once banned.
The Caretos of Podence takes place over three days and celebrates the end of winter and the arrival of spring.
It was recently declared an event of intangible cultural heritage by Unesco after being banned by António Salazar while prime minister of the country decades ago.
The revellers wear brass or wooden masks and dress in costumes made of dyed wool with cowbells on their belts.
In the past it was men behind the masks as the festival was a rite of passage, though a few women would sometimes disguise themselves, but today women and children are encouraged to take part in the updated ceremony.
They revellers shout and chase people, dancing around them, and once cornered the revellers bang their cowbells.
There are a number of events throughout the festival, one being the ritual of the burning of a Shrovetide figure.
The village has a population of some 200, but thousands can turn out to see the spectacle.
All photographs courtesy Octavio Passos/Getty Images