'Run hide fight': Possible shooter at Redstone Arsenal in Alabama

The Redstone Arsenal in Alabama was locked down for more than two hours Tuesday amid reports of a possible active shooter on sprawling military.

"Possible active shooter on the Arsenal. Installation is locked down. Run hide fight," the arsenal tweeted at about 11:30 a.m. ET.

No shootings or injuries were immediately reported, and much of the complex reopened early in the afternoon. The Sparkman Center, headquarters for Army Aviation and Missile Command and scene of the incident, remained closed off.

Redstone Arsenal covers almost eight square miles adjacent to the city of Huntsville and on most weekdays has more than 30,000 workers on site. All gates were closed when the incident was reported, and employees sheltered in place.

Spokesman Christopher Colster said there initially was confusion about whether it might be part of a massive drill scheduled for Wednesday. But he said it was soon confirmed that the incident was unrelated to the drill.

“Our first line of defense is that employee in his cubicle, that when he sees something, he says something," Colster said. “These are very large buildings and it takes time to go through them sometimes. And you’re not only looking for a gunman, but maybe some other threat that may be there.”

Just gave an update over the PA in our building. Active shooter situation still exist. MSFC and Redstone are still on lockdown. — Jonathan Deal (@dealjon) June 27, 2017

The Army Materiel Command and Missile Defense Agency are also housed on the base. The Marshall Space Flight Center, the government's civilian rocketry and spacecraft propulsion research center, is located on grounds and was in lockdown as well.

"Marshall is no longer in lockdown status. Team members may resume normal duties but are asked to avoid the area of Building 5301," the space flight center tweeted at 1:38 p.m. ET.

Taylor Reed, a Huntsville native who works for the Missile Defense Agency, sheltered in a break room and watched local TV news with about 50 other people. His building is near the Sparkman Center.

“We had an 'all hands' with the three star general, or new director, when an alarm started going off. He was, like, is that a fire alarm? Are we ok?” Reed told USA TODAY via email.

Reed said an Army officer soon alerted the group that there was a possible active shooter in the Sparkman Center. Almost everyone knew someone who works there, he said.

Colster said he had no information on whether anyone was taken into custody.

"Our thoughts and prayers are with everybody on the arsenal," Colster said. "We are hoping to hear there are no casualties."