This just in from NotifyNYC:
Notification issued on 10/29/2010 at 12:55 PM. Due to law enforcement activity, 4 Metro Tech has been evacuated. Flatbush Avenue Extension between Tillary Street and Willoughby Street is closed. Expect traffic congestion in the area.
Update: The evacuation appears to have been because of a suspicious package delivered to the Chase Bank branch at Four Metro Tech. The package has been checked and cleared. Flatbush Avenue Extension has been reopened.