A moment of silence is held Saturday at the National September 11 Memorial and Museum in New York. From left are former President Bill Clinton; former first lady and US Sen. Hillary Clinton; former President Barack Obama; former first lady Michelle Obama; President Joe Biden; first lady Jill Biden; former New York City Mayor Michael Bloomberg; Bloomberg's partner, Diana Taylor; and House Speaker Nancy Pelosi.

Chip Somodevilla/Pool/AFP/Getty Images

The week in 40 photos

Updated 7:41 PM ET, Thu September 16, 2021

Chip Somodevilla/Pool/AFP/Getty Images

The past week marked a somber milestone in the United States as we stopped to remember those killed in the September 11 terrorist attacks 20 years ago.

Memorial services were held in New York, Pennsylvania and Virginia, and President Joe Biden visited all three sites. In New York, he was joined by former Presidents Bill Clinton and Barack Obama.

"These memorials are really important," Biden said during his stop in Pennsylvania. "But they're also incredibly difficult for the people affected by them, because it brings back the moment they got the phone call, it brings back the instant they got the news, no matter how years go by."

Take a look at more photos from that day and other major news stories from September 10 to September 16.

Emma Raducanu celebrates after winning the US Open tennis tournament on Saturday, September 11. Raducanu, 18, is the first qualifier in the history of the Open Era to win a major title. She defeated fellow teen Leylah Fernandez in the final 6-4, 6-3.

Elsa/Getty Images

The main booster returns to Earth after a SpaceX rocket launched four people — none of whom are professional astronauts — into the planet's orbit on Wednesday, September 15. This mission, dubbed Inspiration4, is the first orbital mission in the history of spaceflight to be staffed entirely by tourists or otherwise non-astronauts.

John Kraus/Inspiration4

Rapper Lil Nas X attends the Met Gala in New York on Monday, September 13. He went for a succession of rapid costume changes, removing a gigantic velvet robe to reveal a suit of golden armor and then a sparkling golden jumpsuit. See more photos from the red carpet

John Shearer/WireImage/Getty Images

Former Olympic gymnast McKayla Maroney testifies before the Senate Judiciary Committee on Wednesday, September 15. Maroney, Simone Biles, Maggie Nichols and Aly Raisman ripped the FBI and the Justice Department for how FBI agents mishandled abuse allegations brought against Larry Nassar, the former USA Gymnastics team doctor now serving a long prison sentence. "They allowed a child molester to go free for more than a year, and this inaction directly allowed Nassar's abuse to continue," Maroney said.

Saul Loeb/Pool/AFP/Getty Images

Students arrive for the first day of school at the Mott Hall Bridges Academy in Brooklyn, New York, on Monday, September 13. Students in New York City's public schools —the nation's largest school district — were welcomed back to the classroom Monday for full-time, in-person learning, joining school districts across the country confronting a new academic year amid Covid-19.

Chang W. Lee/The New York Times/Redux

A squirrel raids a nut-harvesting machine on a farm near Elkton, Oregon, on Saturday, September 11. The farmer set a live trap with hopes of catching and relocating the bandit.

Robin Loznak/Zuma Press Wire

California Gov. Gavin Newsom makes an appearance after the polls closed in his recall election on Tuesday, September 14. The recall effort was born in partisan anger over his pandemic response, but it ended wit