UPDATE: The mystery F-16 jet fighter seen flying over East Bay cities originated from Naval Air Station Fallon, east of Reno, Nevada.

Public Affairs Officer Zip Upham told CBS San Francisco the pilot was on a “navigation flight,” a routine training mission.

“Navigation flights over the Bay Area happen relatively frequently,” said Upham. “It’s good training. We’ll get a couple of phone calls from people wondering what’s going on.”

Upham also said the pilot was in contact with air traffic control towers in the Bay Area during the flight, which began at Fallon at 5:15 p.m. and returned to base at 6:45 p.m.

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SAN FRANCISCO (CBS SF) — At least one fighter jet was seen and heard roaring over the East Bay Wednesday afternoon.

The jet appeared to be a F-16 Fighting Falcon, with air-to-air missiles attached to the wing tips.

The Federal Aviation Administration had no information about the fighter jet and referred questions to the U.S. Navy.

There was no notice from NAS Lemoore and a spokesperson for Oakland International Airport had no information about the flight.

A representative reached at Travis Air Force Base said he was unaware of any activity, but would check with the base operations.

A spokesperson for Buchanan Field in Concord said they were aware of the F-16 flight but had no information on what the purpose was.

People in Walnut Creek, Danville and other cities in Contra Costa County offered their reactions on Twitter, and said there was more than one jet.

Fighter jets just flew overhead. Changing pants when I get a chance. — andrew_pi (@Bwuh) September 7, 2017

Huh! Fighter jets circling my 🏡??

What trump do now? #DanvilleCa — Dave (@Davo999) September 7, 2017

Fighter jets just went screaming over Walnut Ceeek CA. Brought back memories of living on AF bases — Melissa Van Hoosen (@melvanhoosen) September 7, 2017

The California Capitol Airshow is scheduled this weekend at Mather Airport in Sacramento. No word on whether the plane was part of the event planned for September 9 and 10.