Entertainment Sports Tennis Players at French Open Startled by Sonic Boom as Fighter Jet Breaks Sound Barrier "We both looked at each other and didn't know what it was. It was a weird feeling, for one or two points I thought about it," said Dominik Koepfer By Rachel DeSantis Rachel DeSantis Instagram Twitter Rachel DeSantis is a writer/reporter covering music at PEOPLE. She has held various roles since joining the brand in 2019, and was previously a member of the human interest team. As a music writer, Rachel interviews everyone from rock-and-roll legends to up-and-coming stars for magazine feature stories and digital news stories. Rachel is based in New York City, and previously worked as an entertainment reporter at the New York Daily News after getting her start as an Entertainment Weekly intern. She has a bachelor's degree in journalism from the University of Maryland. People Editorial Guidelines Published on September 30, 2020 12:33 PM Share Tweet Pin Email Dominik Koepfer (R) congratulates Stan Wawrinka with his win in the second round match of the French Open. Photo: Alessandra Tarantino/AP/Shutterstock A sonic boom shook Paris on Wednesday morning, sparking brief confusion and fear among tennis players competing in the French Open. Citizens, athletes and spectators heard the loud clap ring out — and though Paris police confirmed shortly after that the noise was just a fighter jet breaking the sound barrier, it still drew concerns of a possible explosion in a city still reeling from a terror attack just five days prior. Dominik Koepfer was about to serve to opponent Stan Wawrinka when the boom occurred, and video shows both men pause to look up and around to try and find the sound’s source. “It was kind of weird, we both stopped,” the German Koepfer told the Associated Press. “We both looked at each other and didn’t know what it was. It was a weird feeling, for one or two points I thought about it.” Wawrinka, the Swiss player who won the tournament in 2015, said the noise “shocked” him. “For sure, it was a worry,” he said. “I asked the umpire to let me know what it was. Everybody had the answer quite early, so was all good.” Serena Williams Withdraws from French Open Due to an Unhealed Achilles Injury Elina Svitolina and Renata Zarazúa were also competing at Roland Garros when it happened, and Svitolina said it initially confused her. “I was a bit worried because I thought something bad happened,” she told the AP. “I looked at the chair umpire, he was a little bit shocked as well. You never know these days what can happen, what’s going on. It was very strange, very loud, like something big dropped.” RELATED VIDEO: Caroline Wozniacki Says She Considered Driving 15 Hours to See Pal Serena Williams During Pandemic Paris police confirmed on Twitter that the loud noise heard in the area was not an explosion, but a fighter plane that broke the sound barrier. The French Air Force said that the jet was authorized to do so because it was checking on a small civilian plane that had lost contact with air controllers, the AP reported. How to Watch the 2020 French Open — and Which Players to Look Out for The boom came less than a week after a man stabbed two people outside the former Paris offices of newspaper Charlie Hebdo, which was the site of a terror attack that killed 12 people in 2015, the AP reported. Two people were reportedly wounded, and two suspects were arrested, with Interior Minister Gerald Darmanin calling it “an act of Islamist terrorism.” The French Open — which saw star Serena Williams withdraw on Wednesday due to an Achilles injury — kicked off last week and is scheduled to run through Oct. 11.