Four people were arrested at the British Grand Prix at Silverstone on Sunday after breaking into the venue.
The four, who appear to be associated with the environmental group Extinction Rebellion, were detained and arrested after being stopped by track security.
Beforehand, they unfurled a banner with the message, "Act Now", at Club Corner.
A joint statement issued by Silverstone and Northamptonshire Police following Sunday's grand prix read: "During the race, Northamptonshire Police were made aware of four people who had been detained by Silverstone security inside the venue perimeter.
"Officers are working closely with Silverstone Circuit and conducting a full investigation. Four people have been arrested and are in police custody."
A statement on Extinction Rebellion's website said the aim was to send a message that "the world is way off track to stop the climate and ecological emergency" and not to disrupt the race itself.
Additional reporting by PA.
