PHILADELPHIA (CBS) — A group of jets flying in formation over Philadelphia on Monday evening was a military operation, a spokesperson for the FAA said.

What does that mean exactly? No one is saying yet.

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KYW Newsradio received a number of tip calls and photos that show what appears to be a jetliner flanked by two aircraft over each wing.

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(credit: Steve Lindsay)

The North American Air Defense Command typically would scramble fighter jets to intercept or escort a potential threat. But a NORAD spokesman says they were not involved.

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There was no immediate comment from Joint Base McGuire-Dix-Lakehurst.