Demonstrators protesting U.S. Republican presidential candidate Donald Trump have shut down a highway leading to a campaign rally for the candidate near Phoenix, Arizona, Fox News reported Saturday.

The Republican frontrunner is due to appear alongside Joe Arpaio, the octogenarian sherfiff notorious for his racist immigration views.

Three people were arrested, the Maricopa County Sheriff's office said.

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Footage of the demonstration showed a group of protesters with cars blocking forward traffic, holding signs that read: "Dump Trump" and "Shut Down Trump."

The protesters in Arizona parked vehicles sideways on Shea Boulevard, blocking both lanes of traffic into Fountain Hills, Arizona, Maricopa County Sheriff's Office Deputy Joaquin Enriquez told CNN. 

Enriquez described Shea Boulevard as the main artery into the area and the protesters' actions are causing motorists to drive into oncoming traffic as they try to get around them. Traffic was backed up for miles due to the blockage.

"This is causing huge issues for us," Enriquez told CNN, adding that authorities were in the process of towing the vehicles.

"If it continues, obviously, it might lead to arrests," Enriquez said, adding that the arrests would be due to blocking the road, not demonstrating against Trump.