President Joe Biden will visit all three 9/11 memorial sites to commemorate the 20th anniversary of the Sept. 11 attacks and pay his respects to the nearly 3,000 people killed that day.

Biden will visit ground zero in New York City, the Pentagon and the memorial outside Shanksville, Pennsylvania, where United Flight 93 was forced down, the White House said Saturday.

Vice President Kamala Harris will travel to Shanksville, Pennsylvania, for a separate event before joining the president at the Pentagon, the White House said.