WASHINGTON, Jan. 7 (Reuters) — The first round of President Donald Trump's supporters who stormed the U.S. Capitol in a brazen attack on the seat of government were due in court to face charges on Thursday, as police stepped up their search for perpetrators of violence.

In a late-night news conference, Metropolitan Police Department Chief Robert Contee said 47 of the 52 arrests to date were related to violations of Mayor Muriel Bowser's 6 p.m. curfew, with 26 of those involving people arrested on U.S. Capitol grounds.

Several others were arrested on charges related to carrying unlicensed or prohibited firearms.

It was not immediately clear how many people would be arraigned on Thursday.

Contee told reporters late on Wednesday that two pipe bombs were recovered from the headquarters of the Republican and Democratic national committees, as well as a cooler from a vehicle on U.S. Capitol grounds that contained Molotov cocktails.

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A police officer detains a pro-Trump rioter as mobs storm the U.S. Capitol on Wednesday, Jan. 6, during a rally to contest the certification of the 2020 U.S. presidential election results by  Congress. REUTERS / Shannon Stapleton
A police officer detains a pro-Trump rioter as mobs storm the U.S. Capitol on Wednesday, Jan. 6, during a rally to contest the certification of the 2020 U.S. presidential election results by Congress. REUTERS / Shannon Stapleton

A total of four people died on Wednesday during the chaos at the Capitol, including one woman who was shot by a Capitol Police officer.

Contee declined to identify the woman, saying next-of-kin notification was still pending.

Three other people also died on Wednesday because of medical emergencies, he added, and 14 police officers were injured — two of whom remained hospitalized.

It was not clear whether other federal or local police agencies, including the Capitol Police, had made additional arrests.

RELATED: U.S. Congress certifies Biden win after rioters wreak havoc in the Capitol

While the number of people arrested is expected to grow, the initial number paled in comparison with the more than 300 people arrested by police following the June 1 protests in the District of Columbia related to the police killing of George Floyd.

In that incident, baton-swinging police and federal agents fired smoke canisters, flash-bang grenades and rubber bullets to drive protesters farther from the White House, enabling Trump to walk across Lafayette Square and hold up a Bible in front of historic St. John’s Church.

While law enforcement officers were severely criticized for being too aggressive at Lafayette Square, however, the Capitol Police are now facing questions about why they did not do more to secure the Capitol and let many of the rioters later exit the building without arrests.

Armored law enforcement vehicles are parked outside the U.S. Capitol in Washington on Thursday, Jan. 7. REUTERS/Erin Scott
Armored law enforcement vehicles are parked outside the U.S. Capitol in Washington on Thursday, Jan. 7. REUTERS/Erin Scott

Mayor Bowser said police intend to ask the public for help in identifying rioters, many of whom posed for photos inside the Capitol and can be seen in viral videos on social media without masks.

"We will be on the lookout," she said. "Some of them, we think ... have to be held accountable for the carnage."

Late on Wednesday, the FBI also asked the public to submit tips, such as images, videos and other information, to help agents identify people who were "actively instigating violence."

Bowser also extended a public emergency declaration for 15 days, an action she said will allow her to restrict peoples' movements around the city if necessary. Democrat President-elect Joe Biden is slated to take the oath of office on Jan. 20, 13 days from Thursday.

(Reporting by Sarah N. Lynch and Heather Timmons; Editing by Scott Malone and Jonathan Oatis)

Police enforcements arrive to guard the U.S. Capitol in Washington on Thursday, Jan. 7. REUTERS/Erin Scott
Police enforcements arrive to guard the U.S. Capitol in Washington on Thursday, Jan. 7. REUTERS/Erin Scott