Being reported on local TV right now. It’s a four-story building on the Upper East side — or was. It’s completely collapsed into a pile of black rubble; supposedly there are numerous people trapped inside.

They don’t know for sure yet but it looks residential, so there may well be an innocent explanation. Lots of smoke on the skyline. Stand by.

Update: Rumor has it that the building houses medical offices and a beauty salon. The floors of the building “pancaked down” onto each other, says one source, making it nigh impossible for the firefighters to get to people inside.

Update: “Several hundred” firefighters are on the scene.

Update: New York’s CBS affiliate has a report and live video.

Update: Fox is calling it a “fire” but CBS says a “massive explosion” was reported shortly before 9 a.m.

Update: Fox flash: “White House says NYC explosion is not terrorism.”

Update: CBS NY says Con Edison was investigating the smell of gas in the area.

Update: And now Fox says it was a gas explosion that caused it.

Update: None dead, but six are injured. One critically.

Update: Fox says the NYPD is investigating whether a suicide attempt caused the explosion. Presumably this means the person tried to suffocate him/herself with gas, not that they meant to make the building go boom.

Update: Nope. According to ABC, he meant to blow it up.