New York Post is the first to identify the shooter. Not linking it here because, well, New York Post... but it is being floated out there on non-social media.
Edit CNN is speaking to Evan Perez, Senior US Justice Department Correspondant, confirming the information first reported by the New York Post.
Keep in mind, this was something put up on New York Post very shortly after, so...in addition to being the New York Post, it's also one of those cases where early information is wildly incorrect.