Vice President Kamala Harris has taken the oath of office -- becoming first woman, first Black woman and first South Asian American to assume the office of vice president.

Supreme Court Justice Sonia Sotomayor, the first Latina Supreme Court Justice, administered the oath of office to Harris.

Harris had her hand on two bibles. One previously belonged to Regina Shelton, who was like a second mother to Harris and her sister Maya. The second bible belonged to Justice Thurgood Marshall, someone who inspired Harris' career.

International superstar Lady Gaga sang the National Anthem into a gold microphone on the West Front steps of the Capitol for the inaugural ceremonies -- to cheers and applause from the limited audience.

Gaga wore a long sleeve black dress with a pouffy red skirt and golden dove broach with an olive branch across her heart..

Captain Andrea Hall, the first African American female firefighter to become captain of the Fire Rescue Department in South Fulton, Georgia, read the pledge of allegiance.

Sen. Amy Klobuchar, D-Minn., one of the chairs on the Joint Congressional Committee on Inaugural Ceremonies, kicked off the inauguration by acknowledging the attack on the Capitol two weeks ago.

"Two weeks ago when an angry violent mob staged an insurrection and desecrated this temple of our democracy, it awakened us to our responsibilities as Americans," Klobuchar began. "This is the day when our democracy picks itself up, brushes off the dust, and does what America always does: goes forward as a nation, under God, indivisible, with liberty and justice for all."

She also acknowledged the historic nature of Vice President-elect Kamala Harris' ascension to office as the first woman, first Black woman and first South Asian American to be sworn in as vice president.

"When she takes the oath of office, little girls and boys across the world will know that anything and everything is possible," Klobuchar said. "And in the end, that is America, our democracy, a country of so much good, and today, on these Capitol steps and before this glorious field of flags, we rededicate ourselves to its cause."

Guests at Wednesday's inauguration are all wearing masks, a sign of the COVID-19 pandemic which has officially killed more than 400,000 Americans.

And following the deadly insurrection at the Capitol on Jan. 6, several members of Congress are wearing body armor, ABC News Senior White House Correspondent Mary Bruce reported.

ABC reporter Benjamin Siegel saw some Democrats greeting each other by tapping each other on the chest, a “sort of a subtle acknowledgement that they are prepared,” Bruce said.

-ABC News’ Molly Nagle, Benjamin Siegel and Mary Bruce