Workers wearing bulletproof vests, helmets, and scarves to hide their faces dismantled the first of four Confederate monuments planned for removal in New Orleans on Monday.

The first statue was the Liberty Monument, which commemorates whites who tried to topple a biracial post-Civil War government in New Orleans. The 1891 obelisk honoring the Crescent City White League was taken down at 1:25 a.m. Monday morning, under cover of darkness, because of controversy surrounding the removal.

New Orleans Mayor Mitch Landrieu has called the Liberty Monument “the most offensive of the four.”

“If there was ever a statue that needed to be taken down, it’s that one,” he said in an interview Sunday with The Associated Press.

The identities of the contractors removing the monuments are not being revealed due to reported death threats. The removals are taking place late at night or early in the morning to avoid protesters who want the monuments to stay.

New Orleans City Council voted 6-1 in 2015 to approve plans to take the statues down, but legal battles prevented the removal until now. The city is split over the action, which aims to eliminate symbols commonly associated with racism and white supremacy. Some locals view the monuments as part of their history, creating controversy around the removal.

In addition to the Liberty Monument, the city will remove three other statues, individually commemorating Confederate General Robert E. Lee and P.G.T. Beauregard, and president of the Confederate States of America Jefferson Davis. The removed monuments are to be stored and preserved until the city determines an “appropriate” place to display them.

New Orleans contractor Cuzan Services won the contract for removing the statues with a $600,000 bid, more than three times the $170,000 price tag requested by a Baton Rouge contractor last year.

According to a lawyer for the latter contractor, the staff received death threats after submitting the proposal, and according to city officials, the car of one staff member was allegedly set on fire.

That contractor backed out before work even began.

“Given threats and violent acts toward previous contractors, we understand the increased costs can be due to increased risks,” City Hall Press Secretary Erin Burns said in an email. “We remain committed to taking down the Confederate monuments and securing the funds necessary to do so.”

The administration said that the removals will be paid for by an anonymous donor.