It was more than 100 people, but it was a disappointing turnout for sure. And as the OP pointed out the show ran late so by the end of Kreator a lot of people had left to catch the metro. I swear I think some people left after Accept as well. It was my first time at the Howard Theater and man that place is nice. It felt like I should be watching opera or something.
I uploaded a couple of videos I took.
Accept - Fast As a Shark/Balls to the Wall:
Kreator - Phantom Antichrist