Third Boston Marathon explosion a controlled detonation, according to police scanner
Boston law enforcement indicated on the emergency personnel radio scanner at 3:53 p.m. ET that they would be conducting a controlled explosion on the 600 block of Boylston Street, near the Copley Square site of the original explosions that rocked the Boston Marathon earlier Monday afternoon. The explosion occurred around 3:55 p.m. ET.
Other updates from emergency personnel scanner since 3:30 p.m. ET:
The incident command is set up at the Westin Hotel.
"[Placing injured into ambulances] phase seems to be over."
Personnel on the channel suspect the devices may have been placed in trash barrels. "All officers coming into the area are to be cautious of trash containers."
Emergency personnel is trying to move a busload of runners at the Mass Avenue underpass.
Outside incoming agencies will stage at Ring Road and Huntingdon.
No cell phone use, as cell towers are overloaded.
At 3:50, a call was placed for more explosive dogs and swat team members.
At 3:52, armored trucks were en route.