I’m no expert, but to me that looks more consistent with a gas leak. Doesn’t seem to be a central source.
One possibility is it could be a smoke bomb intended to obscure the visibility of the CCTV camera. The haze (smoke) appears to come out of nowhere and happens right before the blast. Its not like you see it rolling down the road toward the camera. Just another oddity I suppose.
Police and witnesses reported hearing a countdown. Gas leak only if deliberate and purposefully triggered.