Sund's resignation is effective January 16, according to a Capitol Police official.
House Speaker Nancy Pelosi on Thursday called for the resignation of the Sund and said the House Sergeant at Arms has told her he is submitting his resignation as well. Michael Stenger, the Senate Sergeant at Arms and Doorkeeper, has resigned as well, Senate Majority Leader Mitch McConnell announced.
Senate Democratic Leader Chuck Schumer had said he would fire Stenger when he became majority leader later this month.
Earlier Thursday, Capitol Police leadership provided first details about the deadly incident that left lawmakers and staff fearful for their lives.
In a statement released Thursday morning, Sund detailed the violent actions of the rioters saying 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 Capitol Police fired on an adult female as "protesters were forcing their way toward the House Chamber where Members of Congress were sheltering in place." The woman was later pronounced dead after being transported to a nearby hospital. The officer involved has been put on administrative leave pending a joint investigation with Capitol Police and the Metropolitan Police Department.
Sund also said Capitol Police responded to reports of pipe bombs and a suspicious vehicle on the southeast corner of the Capitol, adding that the Capitol police "determined that both devices were, in fact, hazardous and could cause great harm to public safety."
The FBI is investigating the incident further.
The Capitol Police revealed for the first time that 13 people have been arrested for "unlawful entry" of the capitol complex, in addition to the owner of the suspicious vehicle. The police said that additional charges may be filed pending further investigation.
More than 50 Capitol Police and metropolitan police were injured during Wednesday's attack, and several have been hospitalized with "serious injuries," according to Sund.
"The violent attack on the U.S. Capitol was unlike any I have ever experienced in my 30 years in law enforcement here in Washington, D.C.," Sund said. "Maintaining public safety in an open environment -- specifically for First Amendment activities -- has long been a challenge."
Lawmakers say they are perplexed at the lack of preparedness among law enforcement given that it had been known for weeks that President Donald Trump was promoting a rally he said was aimed at preventing the certification of Joe Biden's win.
Rep. Mike Quigley, an Illinois Democrat who was locked in the House chamber during an armed standoff between Capitol Police and a rioter, praised the officers who were in the building that put their lives on the line to protect the lawmakers. But Quigley made clear that they were outnumbered and law enforcement was under prepared.
"The Capitol Police I was around did an amazing job under difficult circumstances," Quigley told CNN. "My concern wasn't with how valiant the Capitol Police were. It was that an hour before the debate started, I looked at the throngs of people surrounding different sections of the Capitol -- and said, we don't have enough security."
Quigley added: "I'm no expert in security, but you can tell we were out-manned in an hour before the debate," referring to Congress' proceedings to certify Biden's win.
Others who were in the House chamber with Quigley described the harrowing scene as well. After a rioter broke a window of the door to enter into the chamber, several Capitol Police drew their guns and warned the individual to back away. A desk and chairs had been propped up to block the entry of the rioter, but the lawmakers had no way of knowing if the person was armed or had explosive devices that could turn the scene deadly.
"It was the closest I got to thinking there's a possibility that I could die," said Rep. Raul Ruiz, a Democrat of California. "All we heard was the moving and the intensity. At any moment, someone could have rushed in the door with a semi-automatic."
Immediately when there was a security breach, the top leaders, including Pelosi, were evacuated. Then the House lawmakers who were on the lower level were evacuated. But there were 11 Democrats who were sitting on the upper level of the chamber.
"It was one of those situations when you're in that situation, what would your prayer be?" Ruiz said. "And I prayed. It was one of those moments, where I said, 'If you're going to take me home, take me home.'"
This story has been updated with additional developments Thursday.