Some big celebs were ready to party down with Hillary Clinton ... but it may be a case of party interruptus.

Lady Gaga, Amy Schumer and others descended on the Javits Center in NYC to celebrate the first woman elected president ... breath held.

8:45 PM PT -- Check out the crowd at Javits when they found out Donald Trump won Florida, and took a a sizable lead in electoral votes. No joy in Muddville.