Security operatives in the city of Phoenix, Arizona had a torrid time coping with a crowd of people following clashes as police fired tear gas and stun grenades at protesters in Arizona who were demonstrating against US President Donald Trump.

Reports say the incident occurred outside the downtown Phoenix Convention Center where Trump had just wrapped up his speech at a campaign-style rally for supporters- his first event since white supremacist violence in Charlottesville.

Police claimed protesters threw rocks and bottles at shielded officers, who were armed with batons as a cloudy haze enveloped the night sky with people fleeing the scene as protesters and police clashed.

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“People in the crowd have begun throwing rocks and bottles at police. They also dispersed some gas in the area,” said Jonathan Howard, Phoenix police spokesman.

Reports say Phoenix Mayor Greg Stanton had unsuccessfully called on the president to not hold the rally so soon after the trouble in Charlottesville.

“Toxic Trump,” read one protest sign held up to the president’s supporters streaming into the Phoenix Convention Center downtown. “Lock Him Up!” read another, a reference to earlier campaign chants by Trump and his backers about his election rival Hillary Clinton.