The U.S. Capitol Police said in a statement that Officer Brian D. Sicknick, 42, was injured "while physically engaging with protesters." He is the fifth person to die because of the melee.
The brother of Officer Sicknick released the following statement to ABC News:
"After a day of fighting for his life, he passed away a hero. I would like to thank all of his brothers and sisters in law enforcement for the incredible compassion and support they have shown my family. My family and I hope that our privacy can be respected as we grieve. Thank you."

Houston police chief Art Acevedo, who has also been vocal about condemning the violence at the Capitol earlier this week tweeted condolences Friday morning.
"Rest In Peace Officer Sicknick. We lift you, your family, your colleagues, and your friends in prayer. May your sacrifice never be forgotten and may justice be served," Acevedo wrote.
Rest In Peace Officer Sicknick. We lift you, your family, your colleagues, and your friends in prayer. May your sacrifice never be forgotten and may justice be served.
— Chief Art Acevedo (@ArtAcevedo) January 8, 2021
Loss of USCP Officer Brian D. Sicknick | United States Capitol Police https://t.co/8wTqcbPcuj
Joe Gamaldi, president of the Houston Police Officers' Union, echoed those sentiments, adding "every single person that rioted, destroyed property, assaulted police officers needs to be prosecuted to the fullest extent and locked up."
My thoughts and prayers are with the family of Capitol Police Officer Brian Sicknick. RIP brother we will take it from here.
— Joe Gamaldi (@JoeGamaldi) January 8, 2021
Every single person that rioted, destroyed property, assaulted police officers needs to be prosecuted to the fullest extent and locked up.
Sen. John Cornyn said on Twitter Friday, "Today we all grieve for this brave officer and his family, whose life was needlessly lost because of Wednesday's violent and preventable attack on the Capitol."
Tweet 1
— Senator John Cornyn (@JohnCornyn) January 8, 2021
Today we all grieve for this brave officer and his family, whose life was needlessly lost because of Wednesday’s violent and preventable attack on the Capitol.
Very sad: US Capitol Police officer dies from injuries sustained during riots, officials say https://t.co/lOVqZJvdSd via @ABC13Houston #BackTheBlue
— Senator John Cornyn (@JohnCornyn) January 8, 2021
Sen. Cruz wrote on Twitter about Sicknick's death, "Devastating. Heidi and I are lifting up in prayer the family of the U.S. Capitol Police officer who tragically lost his life keeping us safe. He was a true hero. Yesterday's terrorist attack was a horrific assault on our democracy. Every terrorist needs to be fully prosecuted."
Devastating. Heidi and I are lifting up in prayer the family of the U.S. Capitol Police officer who tragically lost his life keeping us safe. He was a true hero.
— Ted Cruz (@tedcruz) January 8, 2021
Yesterday's terrorist attack was a horrific assault on our democracy. Every terrorist needs to be fully prosecuted. https://t.co/OMH1C1tc5v
Cruz is facing intense calls for his resignation as Texas Democrats said his leading role in efforts to block the certification of President-elect Joe Biden's electoral victory empowered the pro-Donald Trump rioters who breached the Capitol on Wednesday.
READ MORE: Texas Democrats call for Sen. Ted Cruz's resignation for 'acting in bad faith'
In an ABC13 exclusive on Thursday, Cruz insisted that he did not agree and has never agreed with the sitting president's rhetoric that fired up the chaos and left five people, including Sicknick, dead.
In the same interview, Cruz also dismissed the resignation calls, saying that, to him, they were an unsurprising political ploy by the Democrats.
"I do think it's really cynical for them to try and take advantage of what was a tragic event that occurred yesterday in Washington - the terrorist attack on the Capitol was despicable," Cruz said.
The U.S. attorney's office in Washington, D.C., has opened a federal murder investigation into Sicknick's death, three law enforcement sources confirmed to ABC News.
FULL INTERVIEW: Sen. Cruz on own experience inside the Capitol building during riots and whether he believes Pres. Trump should be removed from office immediately
WATCH: Full coverage of the chaos at the Capitol
Images from January 6, 2021