WASHINGTON — U.S. officials vowed to “maximize federal law enforcement presence” in the nation’s capital on Monday night after days of violent demonstrations led to fires across Washington and left scores of businesses with broken windows and dozens of police officers injured.

In a call with governors, President  Trump and Attorney General William Barr also encouraged more aggressive action against those who cause violence during protests across the country following the killing of George Floyd, a handcuffed black man who died after a white Minneapolis policeman pressed his knee into his neck for several minutes even after Floyd stopped moving and pleading for air. The demonstrations have turned violent in several cities, with fires ignited in Lafayette Park across from the White House.

The comments from Trump, Barr and other federal officials appeared aimed at avoiding similar scenes on Monday night, when protesters are expected to gather again. But there are also questions about whether using more aggressive law enforcement measures against demonstrators protesting police brutality would only increase tensions.

Barr told the state leaders that law enforcement officials must “have adequate force” and “go after troublemakers.”

“Law enforcement response is not going to work unless we dominate the streets,” Barr said.

The president urged governors to deploy the National Guard, which he credited with helping calm the situation Sunday night in Minneapolis and demanded that similarly tough measures be taken in cities that also experienced a spasm of violence, including New York, Philadelphia and Los Angeles.

Between the protests and the response to the coronavirus pandemic, the National Guard has been deployed at its highest level in recent history, surpassing the number of troops sent to the Gulf Coast during Hurricane Katrina in 2005. More than 66,700 soldiers and airman have been activated — 45,000 to assist with the pandemic and more than 17,000 to help with the protests.

Other law enforcement resources are also being mobilized.

The Justice Department deployed the U.S. Marshals Service and agents from the Drug Enforcement Administration to supplement National Guard troops in Washington on Sunday. By midnight, Barr had ordered the FBI to deploy its Hostage Rescue Team, an elite tactical unit, to the streets of the nation’s capital, a senior Justice Department official said.

Barr has also directed the federal Bureau of Prisons to send teams of prison riot officers to patrol the streets in Miami and Washington, D.C., said the official, who could not discuss the matter publicly and spoke to The Associated Press on condition of anonymity.

The U.S. Park Police and Secret Service have had dozens of officers out in riot gear in Washington for the last few nights, in addition to the Metropolitan Police Department. U.S. Customs and Border Protection was also sending officers, agents and aircraft around the country to assist other law enforcement agencies “confronting the lawless actions of rioters,” the agency said. The officers were being deployed in several states, though the official declined to provide specific details, citing security concerns.

Several major cities have enacted curfews, and District of Columbia Mayor Muriel Bowser set a 7 p.m. curfew for Monday and Tuesday. Violent demonstrators ignored the 11 p.m. curfew the night before as they set buildings and trash cans on fire and broke into stores to steal items from the shelves.

Most of the protesters have been peaceful and tried to discourage violence. Trump, Barr and others have tried to blame some of the civil unrest on left-wing extremist groups, including antifa, and other “anarchists.” Short for anti-fascists, antifa is an umbrella term for far-left-leaning militant groups that resist neo-Nazis and white supremacists at demonstrations.

The FBI is using its network of regional joint terrorism task forces to “identify criminal organizers,” and federal prosecutors across the country have been instructed to share information and utilize federal riot, arson or terror statutes against any “violent radical agitators” who attempt to hijack protests to cause destruction.

The Justice Department has vowed to treat the “violence instigated and carried out by antifa & other similar groups” as domestic terrorism. Although there isn’t a specific federal domestic terrorism statute, prosecutors could charge other offenses and seek enhanced sentencing.

The FBI has already started questioning rioters who were arrested in several cities to determine whether they committed any federal crimes, the senior Justice Department official said. It is a federal crime to cross state lines to participate in violent riots.

Army Secretary Ryan McCarthy called in the entire D.C. National Guard late Sunday, adding 1,200 soldiers to join about 500 forces that had already deployed in Washington, according to two Defense Department officials. The soldiers will also be armed, the officials said, citing the potential threat from the protesters.

Additional National Guard troops from nearby states were also being called in to help assist in Washington, officials said.

Units from the 82nd Airborne Division’s Immediate Response Force, normally stationed at Fort Bragg in North Carolina, are also expected to deploy to Washington on Tuesday, according to three Defense Department officials. The officials all spoke on condition of anonymity because they were not authorized to discuss the matter publicly.