Gunfire erupted at a crowded birthday bash in a Brooklyn dance hall early Saturday, leaving 15 partygoers wounded, two of them seriously, authorities said.

The shots rang out in a room full of about 100 people who were dancing at a private party in the Flatbush section of the borough, said police spokesman Sgt. Ed Burns.Burns said the gunfire erupted about 6:15 a.m. when an argument broke out among the early morning revelers and eventually spilled out into the street.

"We have no idea what precipitated the argument," the sergeant said.