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.

READ MORE: Girl Attacked By Man On Way To School In Atlantic County, Police Say

Couple Finishes Goal To Eat At Every Cracker Barrel Restaurant In US

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.

READ MORE: Samir Jefferson's Mother Speaks Out After 14-Year-Old Shot 18 Times, Killed In Feltonville

(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.

FBI: Women Dressed As Nuns Wanted For Attempted Armed Bank Robbery

MORE NEWS: Family, Friends Hold Candlelight Vigil For Slain Temple University Student Samuel Collington

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