A threat prompted the U.S. Navy to evacuate workers from two Philadelphia facilities Tuesday morning and raise the threat level to imminent.
U.S. officials told NBC News they heightened security measures at the Philadelphia Navy Yard in South Philadelphia and Naval Support Activity Philadelphia center in Northeast Philly after the FBI informed the military of a potential terror threat.
In turn, officials raised the threat level for those facilities from Bravo to Charlie — the second highest level — while evacuating workers around 10:20 a.m. Some workers said they were suddenly told they had to leave without being given an explanation.
By noon, SkyForce10 captured crews blocking the entrance to the Northeast Philly facility with concrete barriers.
The Navy took the lead on the investigation as NCIS confirmed that they were looking into a threat at the Northeast Philly supply facility. None of the agencies described the nature of the threat.
— U.S. Navy (@USNavy) June 16, 2015
Shortly after noon, Homeland Security gave the all clear but didn't reveal any further details. The FBI deemed the threat non-credible.
The facilities provide "operation ready, secure shore infrastructure," according to the Navy.
Other businesses in the Philadelphia Navy Yard remained open Tuesday as Philadelphia Police and federal authorities investigated.