CNN reporters inside the stadium reported hearing several loud bangs. A message on the scoreboard initially told fans to stay inside the baseball park, but it has since been updated to say that it is safe for fans to leave the stadium.
CNN has contacted the Metropolitan Police Department and Washington Nationals for further comment.
Nationals-Padres Series Game 3 which was originally scheduled to start at the same time on Sunday, but will instead be played at the end of the suspended game, the team said.
This is a developing story and will be updated as more information becomes available.
CNN’s Sam Feist, Lindsey Knox, Aya Elamroussi and Andy Rose contributed to this report.