A US military post in Alabama which was on lockdown amid reports of a possible active shooter has been given the all-clear.
Officials said there were no confirmed injuries or arrests after the incident at Redstone Arsenal.
A safety drill was planned for Wednesday but Redstone spokesman Christopher Colster said he was not sure "at this point what happened" at the base near Huntsville. He said there would be an investigation.
Possible active shooter on the Arsenal. Installation is locked down. Run hide fight.
— Redstone Arsenal (@TeamREDSTONE) June 27, 2017
“We do not believe there is a threat or we would not have opened the installation back up,” he said.
Earlier, Mr Colster had said the report of a shooter was not part of any exercise.
In a tweet announcing the possible shooter, the base said: “Possible active shooter on the Arsenal. Installation is locked down. Run hide fight.”
Police cars with flashing lights blocked entrances to Redstone, which also has facilities used by federal law enforcement agencies.
Images on social media showed an ambulance and what appeared to be civilians standing outside the Sparkman Centre, which includes multiple buildings with offices, an auditorium, cafeteria and an interior courtyard.
But Huntsville hospital officials said they had not heard of any incoming patients, local TV stations reported.
More than 30,000 government employees, civilians and contractors work daily at Redstone.
It is home to US army missile defence programmes and other military offices.
Nasa’s Marshall Space Flight Centre, which oversees rocket propulsion operations, is also located at Redstone.
AP