WASHINGTON — The US Capitol Police confirmed the death of one of their officers late Thursday from injuries suffered when a mob of President Donald Trump's supporters stormed the Capitol a day before.

Capitol Police said in a statement that Officer Brian D. Sicknick died at approximately 9:30 p.m. ET Thursday "due to injuries sustained while on-duty."

The death is being investigated by the DC Metropolitan Police Department's homicide branch, the US Capitol Police, and their federal partners.

"Officer Sicknick was responding to the riots on Wednesday, Jan. 6, 2021, at the US Capitol and was injured while physically engaging with protesters. He returned to his division office and collapsed. He was taken to a local hospital where he succumbed to his injuries," the statement read.

Sicknick had joined the Capitol Police in July 2008, and most recently served in the department's First Responders Unit.

"The entire USCP Department expresses its deepest sympathies to Officer Sicknick's family and friends on their loss, and mourns the loss of a friend and colleague," Capitol Police said.

Sicknick is the fifth person to die as a result of Wednesday's insurrection. One woman was shot and killed by Capitol Police as the crowd breached the building and three others suffered medical emergencies that proved fatal.

Shortly after 1 p.m. ET Wednesday hundreds of pro-Trump protesters pushed through barriers set up along the perimeter of the Capitol, where they tussled with officers in full riot gear, some calling the officers "traitors" for doing their jobs.

About 90 minutes later, police said demonstrators got into the building and the doors to the House and Senate were being locked. Shortly after, the House floor was evacuated by police. Vice President Mike Pence was also evacuated from the chamber, where he was to perform his role in the counting of electoral votes.

An armed standoff took place at the House front door at about 3 p.m. ET, and police officers had their guns drawn at someone who was trying to breach it.

As a result of the episode, US Capitol Police Chief Steven Sund is resigning. He said in a statement earlier Thursday that Capitol Police and other law enforcement officers were "actively attacked" with metal pipes and other weapons.

"They were determined to enter into the Capitol Building by causing great damage," Sund said.

"The violent attack on the US Capitol was unlike any I have ever experienced in my 30 years in law enforcement here in Washington, D.C.," he added. "Maintaining public safety in an open environment — specifically for First Amendment activities — has long been a challenge." — Courtesy CNN