Update: An investigation has determined that reports of shots being fired and of an individual with a firearm were deemed “not credible,” said Army Col. Thomas Holliday. According to Redstone Arsenal’s garrison commander, no gunman was ever located and no one was injured in the incident.

The gates have been opened but many questions remain after reports of an active shooter at the Redstone Arsenal military base in Huntsville, Ala. This is what is known at this point:

The base sent out a tweet warning of a “possible active shooter” situation, and the base was put into a lockdown, with the command to “Run hide fight.” Three hours later, the lockdown has been lifted and a Redstone Arsenal spokesman declares there is no present threat. Chris Colster added the situation is “not a terrorist event.”

Possible active shooter on the Arsenal. Installation is locked down. Run hide fight.

— Redstone Arsenal (@TeamREDSTONE) June 27, 2017

Redstone had been scheduled to hold an active shooter drill tomorrow, but this incident was not a drill. 

The situation is centered around the installation’s Sparkman Center. The area around Sparkman Center remains sealed off. However, gates around the base have been opened and cars are now entering and exiting. 

Several tweets from those claiming to be on Redstone have made reference to a “female shooter” and at least one hostage. There are also reports the incident may stem from a domestic situation. These reports are unconfirmed. 

The base has now released a vague statement about the incident.

Spokesman Colster says the investigation is ongoing and asks for “prayers for those involved in this situation.”