The Redstone Arsenal military installation in Huntsville, Ala. had its lockdown lifted, according to the installation's official Twitter account.
Details surrounding the incident remain unclear. However, officials tweeted Tuesday morning and urged everyone to “run, hide, fight" after reports of an active shooter.
Possible active shooter on the Arsenal. Installation is locked down. Run hide fight.
— Redstone Arsenal (@TeamREDSTONE) June 27, 2017
A spokesperson told AL.com that no one is in custody but there is still an investigation into a possible active shooter incident.
CBS affiliate WHNT reported that officials confirmed there was “some sort of situation” at the center. There was an active shooter training exercise scheduled for this week but the station reported the incident was not related.
Redstone Arsenal spokesperson Christopher Colster told AL.com that he was not aware of any reported injuries but that the location of the incident has not been determined. An ambulance was sent to the facility, CNN reported.
The post has more than 40,000 employees working throughout a 30,000-acre facility, according to AL.com.