On Broadway, as the saying goes, the show must go on — even in a blackout.

Saturday night’s five-hour power outage sent thousands of show-goers out of darkened theaters and crowding onto the sidewalks, where many were delighted to found themselves serenaded by similarly evicted cast members.

The cast of Waitress staged one such impromptu concert.

This year’s Tony winner for Best Musical, Hadestown, was well represented.

Even passersby — without tickets — were treated to a show.

The Millennial Choir and Orchestra, meanwhile, entertained crowds outside Carnegie Hall.