Phoenix- Police fired pepper spray to disperse protesters outside a presidential rally in Phoenix, Arizona.

Police have not given an estimate of the number of protesters, but Arizona media said there were several thousand.

“People in the crowd have begun throwing rocks and bottles at police,” Phoenix Police Department spokesman Sergeant Jonathan Howard said.

“Police have responded with pepper balls to disperse the crowd and stop the assaults,” he added.

Four people were arrested during the protest, Phoenix Police Chief Jeri Williams said during a news conference.

Police called on the crowds to disperse.

any of the protesters quit the scene, while dozens of police sought to clear remaining protesters from the downtown area.

A Reuters witness saw at least one person sat on a sidewalk, in handcuffs.