A US military post in Alabama was put on lockdown following reports of an "active shooter" on site. The Redstone Arsenal base in Huntsville advised those in the area to "run hide fight" in a message posted to Twitter.
Officials connected to Redstone Arsenal confirmed to local media there was "some sort of situation" near the Sparkman Center.
Spokesperson Christopher Colster told WAFF-TV said there no confirmed casualties.
Alabama governor Kay Ivey said she was being updated on the situation at Redstone. She added: "I will continue to closely monitor and pray for a peaceful and quick resolution."
The FBI confirmed they sent agents to the scene.