Something similar happened in the school at which I was the TV production teacher...but thank the gods it didn't happen when my class was in session!
Turns out, it was the TV technician flipping channels & came across some porn. It was only on for a flash.
The tech was not fired. I wish he was, from the first day of school. He made my life & the students' lives miserable, by overstepping his bounds. But he was such an ass-kisser, the principal loved him. Idiot principal was "forced" to retier early a year or so after I left.
But I digress....