Updated at 9:05 p.m. ET
Senate Majority Leader Mitch McConnell says he requested and has received Senate Sergeant at Arms Michael Stenger's immediate resignation.
The position, as the highest-ranked law enforcement officer in the Senate, will be filled by Jennifer Hemingway, the current Deputy Sergeant at Arms.
"Deputy Sergeant at Arms Jennifer Hemingway will now serve the Senate as Acting Sergeant at Arms, pursuant to statute," McConnell said in a statement Thursday evening. "I thank Jennifer in advance for her service as we begin to examine the serious failures that transpired yesterday and continue and strengthen our preparations for a safe and successful inauguration on January 20th."
This decision comes on the heels of one of the darkest days in congressional history as pro-Trump rioters stormed the Capitol in its largest security breach by a mob since the War of 1812. The events resulted in a woman being shot and killed by U.S. Capitol Police.
Earlier Thursday McConnell announced the need for a "painstaking investigation" into the security issues of Wednesday.
"Yesterday represented a massive failure of institutions, protocols, and planning that are supposed to protect the first branch of our federal government," McConnell said in a statement.
Before Stenger offered his resignation, Senate Minority Leader Chuck Schumer said he would fire Stenger once Democrats regained control of the upper chamber.
"If Senate [Sergeant-at-Arms] Stenger hasn't vacated the position by then, I will fire him as soon as Democrats have a majority in the Senate," Schumer said in a statement to NPR.
Schumer is poised to become the Senate majority leader after two Democrats, the Rev. Raphael Warnock and Jon Ossoff, won their Senate runoff elections Tuesday in Georgia.
Additional security steps are being taken following Wednesday's events at the U.S. Capitol.
A "7-foot non-scalable fence" will be built around the building, according to a statement by Army Secretary Ryan McCarthy. The fence will stay up for 30 days. More than 6,000 members of the National Guard will also deploy to the Washington, D.C., area over the weekend.