What can it be? My guess the full-scale invasion of Yamada Yōkō and Nihon Miraise offices by the black suit crowd from the Tokyo Prosecutor's Office.
Later - Nope, seems to be a fire in a seven-story building in Shiba. At least half the helicopters seem to be rescue units in line to pull folks off the roof.
Still, the black suit crowd did march into Nihon Miraise today.