Several dozen people arrested in the violent chaos at the U.S. Capitol made their first appearances in court Thursday as authorities vowed to track down additional suspects and also determine why the mob that stormed and vandalized the building was able to easily overwhelm the police officers guarding it.

In D.C. Superior Court, 40 defendants were charged with unlawful entry of public property and were notified that prosecutors are reviewing evidence of an additional charge of curfew violation. Most of the defendants came from outside of the Washington region — including Oregon, Florida, Wyoming, Connecticut and Pennsylvania — though some were from the District, Maryland and Virginia.

One person arrested was charged with possessing a “military style automatic weapon” and 11 molotov cocktails, prosecutors said. Another defendant was charged with assaulting a police officer with a hockey stick. Yet another, who needed a Russian interpreter, told a judge, “I don’t know what unlawful entry you are referring to.”

They had been among thousands of demonstrators who marched on the Capitol in support of President Trump’s false claim that he lost the Nov. 3 election because of massive voter fraud. Although prosecutors in some cases sought to have them held in jail pending prosecution, most were released on their own recognizance.

The 40 defendants in Superior Court were accused of violating D.C. law, including being out after a 6 p.m. curfew imposed by the city.

As of early Thursday evening, four other people, charged with federal crimes, appeared in U.S. District Court, including a Maryland man accused of possessing a firearm after curfew on Capitol grounds just outside the Capitol Visitor Center — a 9mm handgun with a round in the firing chamber. Prosecutors said he also was carrying two fully loaded 12-round magazines, wearing a bulletproof vest, and carrying a gas mask and pocket knife in his backpack. Police said in an affidavit that the man told officers that the gun was for personal protection and that he did not intend to hurt anyone.

Meanwhile, D.C. Police Chief Robert J. Contee III vowed that his department would arrest “each and every one of the violent mob,” and said that investigators are circulating information publicly and to FBI offices nationwide, including photos of rioters destroying property inside the Capitol on Wednesday. He said the department is offering a $1,000 reward for any tip leading to the arrest of a rioter.

Contee’s remarks echoed a pledge by acting attorney general Jeffrey A. Rosen.

“The Department of Justice is committed to ensuring that those responsible for this attack on our Government and the rule of law face the full consequences of their actions under the law,” he said in a statement.

Rosen said his office has been working with numerous law enforcement agencies to identify and charge perpetrators.

“We will continue to methodically assess evidence, charge crimes and make arrests in the coming days and weeks,” Rosen said.

The FBI also said that it is asking people in areas where explosive devices were found whether they would share any video recordings of surroundings with investigators. D.C. police and the FBI also released several photos of rioters, hoping the public can help identify them to make arrests.

At a news conference, Michael R. Sherwin, the acting U.S. attorney for the District, voiced “concern” at the relatively small number of rioters who were detained by police in the Capitol. As a result, he said, federal authorities face the daunting task of identifying, locating and obtaining arrest warrants for a large number of suspects, which he said could occupy investigators for months.

“Hundreds of people flooded the Capitol and were not [handcuffed] by police,” Sherman said. “I don’t want to be Monday morning quarterbacking to say why they didn’t do it, but it made our job more difficult.” He said, “I can’t explain why they weren’t” detained.

“We have a lot of lessons to learn from this,” Sherwin said. “I think we are going to learn from this over the next several months, if not years.”

Sherwin said authorities “obviously” anticipate making more arrests as investigators develop information about additional suspects in coming days and months. He said a large amount of government paperwork along with electronic devices and other items were stolen from congressional offices during the disturbance, which “could have national security implications.”

Sherwin also responded to criticism of the perception of how the mob scene was handled at the Capitol versus arrests that were made over the summer during Black Lives Matter protests. Sherwin said that during the summer, federal prosecutors processed 174 criminal cases. He said in just one day, his office charged 55 cases and expect more in the coming weeks and months. “I just want to give you a comparison to show how seriously we are taking this,” Sherwin said. “I don’t want that to get lost.”

U.S. Capitol Police have been heavily criticized by law enforcement experts for the evident lack of preparedness by the 1,700-member department. On Thursday morning, in his first public statement about his department’s performance, Chief Steven Sund described his officers as “heroic” and praised their “professionalism and dedication.” Sund resigned later that evening.

Sund said the mob’s storming of the Capitol was unlike any incident he has experienced in three decades of law enforcement in the Washington area. More than 50 D.C. and Capitol Police officers were injured, with several hospitalized, police said.

Authorities said a Capitol Police officer shot and killed a pro-Trump demonstrator, Ashli Babbitt, 35, of San Diego, who was among a group of rioters trying to break through an interior Capitol door near the House Speaker’s Lobby. The shooting is being investigated by D.C. police, and the officer has been placed on administrative leave.

“The USCP had a robust plan established to address anticipated First Amendment activities,” Sund said. “But make no mistake — these mass riots were not First Amendment activities; they were criminal riotous behavior.”

He said “thousands of individuals involved in violent riotous actions” attacked officers with metal pipes, chemical irritants and other weapons. He said officers responded to reports of two pipe bombs, including one outside Republican National Committee headquarters, and a suspicious vehicle at the 300 block of First Street SE.

After determining that both devices were hazardous, a police bomb unit disabled them and turned them over to the FBI, Sund said.

The suspicious vehicle, reportedly a truck loaded with weapons, ammunition and bombmaking materials, was cleared of any hazards and its owner was arrested, police said.

“The USCP is conducting a thorough review of this incident, security planning and policies and procedure,” Sund said.

D.C. police said they arrested 69 people from at least 20 states and the District on Wednesday afternoon through early Thursday, most on curfew and unlawful entry charges. One is a juvenile.

That brings the number of people arrested by D.C. police since Tuesday afternoon to at least 79. The numbers do not include at least one arrest by the U.S. Park Police for a firearms violation at Freedom Plaza. Capitol Police also announced 14 arrests for charges including assaults on police officers, unlawful entry and firearms violations.

Since Tuesday, D.C. police have arrested at least six people on firearms charges, including several at Freedom Plaza and one aboard a multicolored school bus from North Carolina that police stopped after receiving a tip. Police said they found a rifle, a handgun and ammunition aboard.

Two of the more than 79 people arrested during unrest since Tuesday were accused of illegally possessing weapons such as metal knuckles and blackjacks. Twenty-five people were charged with curfew violations and unlawful entry onto Capitol grounds. It is unclear if any of those people were inside the Capitol itself.

“The violence and destruction of property at the U.S. Capitol building yesterday showed a blatant and appalling disregard for our institutions of government and the orderly administration of the democratic process,” FBI Director Christopher A. Wray said, adding that “we will hold accountable those who participated” in the siege.

He said, “Our agents and analysts have been hard at work through the night gathering evidence, sharing intelligence and working with federal prosecutors to bring charges.”

Emily Davies, Katie Mettler, Dan Morse and Peter Hermann contributed to this report.