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WRIGHT-PATTERSON AFB, Ohio (WDTN) — A lockdown that began at Wright-Patterson Air Force Base around 9:25 Thursday night was finally lifted just after 1:30 a.m. Friday.

The “all-clear” was given over the loudspeaker after a lockdown lasted more than four hours.

88th Air Wing Base Installation Commander Col. Patrick Miller spoke with reporters around 2 a.m. Friday. You can watch that full news conference here:

Bob Purtiman, Chief of Public Affairs at Wright-Patterson Air Force Base told 2 NEWS around 1:15 a.m. Friday security forces were still searching the 850,000 square-foot NASIC Building 856 after two people reported they heard gunshots in the area. An alert was sent out to all base personnel stating and Wright-Patterson AFB said an investigation into a possible active shooter began. An alert sent to base personnel instructed them to immediately seek shelter in the nearest building away from the threat.

Purtiman said the sweep was taking a long time as security forces had to wait for access to some areas of the NASIC building. He also said there were no reports of anyone injured. No evidence of gunshot being fired had been found, but Purtiman pointed out the threat report was “credible.”

This is a developing story. 2 NEWS’s previous update is below:

Base officials said they’ve completed an initial sweep of the building and are conducting a second sweep but the lockdown remains in place.

2 NEWS began receiving calls and emails around 9:30 p.m. reporting a loudspeaker announcement alerting those on the base of the lockdown. Though 2 NEWS reporter Allison Gens has seen multiple law enforcement agencies leave, the alert is still playing and people are still being turned away at the gate.

WPAFB officials said in an email that at roughly 9:25 p.m. emergency responders were alerted to reports of an active shooter at NASIC in Area A. It went on to say that security forces were sweeping the building and that the base was on lockdown.

At 11 p.m., base officials provided an update on social media, saying, “We understand there are concerns and questions. Our first priority is to protect our people. All of our military and civilian employees are trained to quickly assess the situation and take appropriate action. More info will be provided once available.

2 NEWS reporter Caroline Morse is at the media staging ground at the Hope Hotel near the base and said that Dayton and Beavercreek Township police cruisers are present. We reached out to several other law enforcement agencies who told us that they were not asked for help.