WATERTOWN ON LOCKDOWN AS POLICE HUNT BOMBING SUSPECT

The town of Watertown, Mass. is on lockdown as police pursue one of the Boston Marathon bombing suspects.

The MBTA is also shutting down all transportation in the city.

Police are calling for armoured vehicles to a specific intersection. This while busloads of residents being evacuated nearby.

— Doug Saunders (@DougSaunders) April 19, 2013

The man known as Suspect 2 evaded police after a car chase and shootout that killed Suspect 1. Here, authorities believe, is his photo via a 7-11 security camera snap from earlier this evening:

SWAT teams are coming the area as bomb squads clear the street of explosive devices that suspects threw at police during the car chase.

“We believe this to be a terrorist," Boston Police Commissioner Edward Davis said. "We believe this to be a man who has come here to kill people. We need to get him in custody.”

NBC's Pete Williams reports that "authorities say [the suspects] came from overseas... had overseas military training... been here about a year."