Jonah Hill Witnesses Bloody Street Birth in NYC

So there we were ... walking around NYC today when we saw a woman giving birth in the middle of a park. And get this, Jonah Hill was there too ... taking pictures.

The whole situation was pretty crazy ... our photog stumbled upon the scene by pure happenstance ... where emergency workers had just loaded the woman into an ambulance.

But after the dust settled ... we randomly noticed Jonah snapping a cell phone pic of the birthy aftermath near the bench where the woman was sitting when she went into labor.

We tried to ask Hill about the situation ... but he seemed a little too embarrassed to talk and beat a hasty exit with his pretty lady friend.

We don't blame ya for taking pictures, J. It's not like that kinda stuff happens every day.

3:45 PM PT -- Jonah just tweeted about our awesome encounter. PLACENTA.