Authorities are investigating reports of an active shooter at a US Army post in Alabama.

The gates were all locked at the Redstone Arsenal, a facility near Huntsville, ABC News reported.

There was a scheduled active shooter drill planned for Wednesday, but a tweet from the arsenal said the situation was real.

The Arsenal’s Twitter account had a post that read, “installation is locked down. Run hide fight.”

Arsenal spokesman Christopher Colster told the network there are no reported injuries that he is aware of.