(CNN) -- Super Bowl fans in Tucson, Arizona, caught a different kind of show during Sunday's big game.

Just as Cardinals' superstar Larry Fitzgerald watched himself sprint into the end zone on the stadium's Jumbotron during Sunday's Super Bowl, 10 seconds of eye-popping pornographic imagery "flashed" across the screens of those watching at home.

"We are mortified by last evening's Super Bowl interruption, and deeply apologize to our customers for the inappropriate programming," Comcast Cable said in a written statement.

"Our initial investigation suggests this was an isolated malicious act," the statement added.

Comcast, and several local television stations that carried the signal, say they are currently investigating what caused the interruption.

"It appears this material was only viewed by some Comcast customers," local Tucson television station KVOA-TV said in a written statement.

Television station KVOA added "when the NBC feed of the Super Bowl was transmitted from KVOA to local cable providers and through over-the-air antennas, there was no pornographic material," KVOA President and General Manager Gary Nielsen said in a separate statement.

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