Watched this live last night. We concluded it was a pop off valve perhaps from a boiler. A shhh sound could be heard immediately after the “explosions.” There were FBI police cars parked at the building. The “smoke” dissipated quickly and no smell of smoke reported. It was most likely steam, not smoke.
While I was posting, I see a statement has been released confirming what we concluded.
The exact same sound a laptop from hell would make - yes?