The Air Force is investigating a bomb threat that emptied wing headquarters and the base exchange Thursday morning at Yokota Air Base, the airlift hub in western Tokyo.

The 374th Airlift Wing sent a “bomb threat, all clear” email notice to the base community shortly before 1 p.m., about two hours after ordering evacuations for several buildings on the base, which also serves as headquarters for 5th Air Force and U.S. Forces Japan.

“Security Forces completed sweeps of the affected areas and declared them safe to resume normal operations,” the wing said in a statement Thursday afternoon.

The incident is under investigation, base spokesman 1st Lt. Danny Rangel told Stars and Stripes via text message.

The 374th Security Forces Squadron initially ordered evacuations at wing headquarters, the Enlisted Club, a residential tower and several other buildings. Several dozen people, including service members and American and Japanese civilian employees, gathered a short distance from the evacuated buildings.

“I was just driving and a friend was walking outside saying everyone in the area I was going to was evacuated due to some sort of threat at the e-club,” Air Force spouse Rylan Matosky told Stars and Stripes via Facebook Messenger on Thursday.

Security forces later ordered an evacuation of the Yokota Community Center, where the Army and Air Force Exchange Service and base commissary are housed, along with other retailers and a food court. Evacuees there were directed to a rally point near the base flight line.

Yokota’s main gate and a gate used for deliveries and by outside contractors, both along busy Route 16, were closed, along with base streets near the affected sites.

“We have a real world incident and we are asking our base community to follow instructions from security personnel,” Rangel told Stars and Stripes via text message just after 11 a.m.

In their afternoon statement, Yokota officials said all affected gates and roads had reopened for regular traffic.

“No injuries were reported as a result of this incident,” the statement said. “Yokota Air Base members are advised to continue to follow the directions of security personnel and remain vigilant for suspicious activity and to report incidents to [security forces].”

Stars and Stripes reporter Kelly Agee contributed to this report.