Softball fans sang the Star-Spangled Banner because the organizers wouldn't play the national anthem during a game in Fresco, California.
The incident, which took place last May 25, 2018, was captured on video that was later posted to Twitter.
'Clovis and Buchanan softball about to play for D-I title, but before that, it was announced there will be no national anthem. There were boos and the crowd did this,' Anthony Galaviz captioned the clip, which he posted on May 25, 2018.
In the clip, the crowd can be seen stading up and singing the national anthem without any music playing in the background.
After singing, they clapped their hands and erupted into cheers. The clip has been retweeted nearly 400 times.
It is a tradition in the United States to play the national anthem before sporting events. People are expected to stand with their right hand over their heart.
The singing of the national anthem before games has become controversial since 2016 after a number of athletes used it as an opportunity to protest police brutality and racial inequality
San Francisco 49ers quarterback Colin Kaepernick set off the series of national anthem protests when he refused to stand - he sat and later kneeled - when the national anthem was played before his team's preseason games of 2016.
Members of various NFL and other sports teams also made similar silent protests throughout the 2016 season.
The NFL protests reached its peak on September 24, 2017 when more than 200 players sat or kneeled in response to President Donald Trump's statement calling on owners to fire protesting players.
In response, the NFL commissioner and the NFL team owners implemented a new policy requiring all players to stand during the singing of the national anthem or to stay in the locker room if they didn't want to participate in it.