Police said they used pepper spray twice outside a Donald Trump rally in Kansas City, Missouri, on Saturday.
In a Twitter post referring to the incident, Kansas City police did not clarify if the use of pepper spray was on demonstrators or supporters of the Republican presidential candidate.
The email you need for the day's
top news stories from Canada and around the world.
Police also said they had arrested two people for refusing to follow the law.
While a boisterous group of protesters gathered outside the theatre where Trump spoke in downtown Kansas City, the event concluded without significant incident.
Police say the majority of people exercised their rights to gather peacefully.