Thank you!
Tourists are still in the Grande Place taking selfies with the giant Christmas tree. But the side streets that lead to the Place are being shot off and one guy who was dining in a restaurant on one said they were escorted out of the restaurant and the street was cordoned off.
This center of Bruxelles is at the highest security level 4 while the rest of Belgium is at level 3.
Me thinks this was a planned shut down and investigate, not a response to some sort of attack. Which is why they must have started at a specific late evening time, and plan to perhaps take all night, so they closed the metros and schools.