UPDATED, 1:24 p.m.: WBZ Radio's Carl Stevens tweeted that a phoned in bomb threat forced the response and evacuation at 200 West St.
UPDATED, 1:17 p.m.: Waltham Police now say all units are clear from the scene.
UPDATE, 12:21 p.m.: Waltham Police have confirmed, via Twitter, that they are actively investigating at incident at 200 West St., the home of A123 Systems. They did not specify any details.
Authorities are evacuating 200 West St. on reports of a suspicious package, according to Twitter reports.
The first report came in at around 10 a.m. and now the building is being evacuated, according to Twitter reports.