Clashes erupted between white nationalist groups and counter-protesters Saturday as thousands began gathering for an alt-right rally in downtown Charlottesville, Va., beside the endangered statue of Gen. Robert E. Lee.

Police estimated 2,000 to 6,000 people would attend the gathering of white nationalists, neo-Nazis, alt-right activists and pro-Confederacy groups. Thousands more counter-protesters were also anticipated.

Police were on hand to maintain order and Gov. Terry McAuliffe placed the Virginia National Guard on standby.

The pushing and shoving, mainly between white nationalists and anti-fascist groups, erupted as crowds streamed toward the noon rally at Emancipation Park. At one point, dozens of people began used wooden poles from their flags and banner as weapons. Protesters on one side of a square held up anti-fascist signs, and Black Lives Matter banners, while groups on the other displayed Confederate flags and iron cross banners.

As homegrown militia groups arrived with weapons and rifles, some protesters wearing helmets and flak jackets engaged in skirmishes behind riot-police-style plastics shields.

The rally was bolstered by a federal court injunction Friday night. It was called to protest the city's decision to remove the statue of the Confederate general, but also served as a rallying cry for the far right.

A spontaneous march by torch-wielding protesters onto the University of Virginia campus Friday night was broken up by police as an unlawful assembly after scuffles broke out and pepper spray filled the air.

U.S. District Judge Glen Conrad issued an injunction late Friday in a lawsuit filed against the city by the American Civil Liberties Union on behalf of right-wing blogger Jason Kessler, a local resident.

Conrad ruled that the city's attempt to revoke Kessler's "Unite the Right" rally permit and move the protest to another park "was based on the content of his speech.”

The judge noted the city did not try at the same time to move counter-protesters to another location.

Police said some 1,000 first responders, including law enforcement, will be on duty during the weekend. McAuliffe, the governor, said the Virginia National Guard would be on standby "to respond if needed.”

McAuliffe, a Democrat, said he would prefer that no one shows up at the "Unite the Right" rally.

"I want to urge my fellow Virginians who may consider joining either in support or opposition to the planned rally to make alternative plans," he said.

The Charlottesville City Council voted in May to sell the Lee statue, but a judge issued a temporary injunction that blocked the city from moving the statue for six months, The Daily Progress reported.

Police chief Al Thomas said the unfolding events created a "lot of anxiety" in the community, but he felt it had sufficient resources to meet the "significant challenge."

City authorities were particularly alarmed by Friday night's march by hundreds of white nationalists who gathered at the feet of a statue of Thomas Jefferson on the UVa. campus, chanting "You will not replace us."

Fights broke out as some marchers bearing tiki torches swung them at others, the Daily Progress reported. One person was arrested and several were treated for minor injuries, the paper reported.

UVa. President Teresa Sullivan said she was "deeply saddened and disturbed by the hateful behavior" displayed by the marchers.

Mayor Mike Singer, who opposed the downtown rally, said the city would honor the judge's ruling, but added there is "no constitutional right to incite or promote violence by anyone who will be gathered this weekend.”

"Democracy may be noisy and it may be messy, but it remains the best system of government that people have figured out to use to govern themselves,” he said.

The ACLU of Virginia and the Albemarle County-based Rutherford Institute, which backed Kessler's suit, said in a letter to city officials that while the message of the "Unite the Right" rally "may raise strong feelings of opposition among area residents and political leaders, that opposition can be no basis for government action that would suppress the First Amendment rights of demonstrators who have acted according to the law.”

In May, Kessler was among three people arrested during a counter-protest that followed an alt-right demonstration. He was arrested for disorderly conduct, police said, according to The Daily Progress.