I have a series of running updates in the post
below about an on-going shooting incident at MIT. That's in Cambridge, just across the Charles River from Boston. I want to stress, however, there is no evidence that this is related to the bombing investigation.
Gunshots were heard on the campus about an hour and 20 minutes ago. A MIT police officer was seriously wounded and has been taken to Mass General. Police have cordoned off the area and there appears to be an active manhunt underway.
Late Update - 12:08 AM: Multiple local news reports
say the police officer has died.