The married couple suspected of killing 14 people at a social services center had built more than a dozen pipe bombs and stockpiled thousands of rounds of ammunition, officials said Thursday, and they fired as many as 150 bullets at victims and police officers in a rampage that shattered a quiet day and ended in their own deaths. The F.B.I.’s counterterrorism division has begun looking into the case, two law enforcement officials said Thursday. The suspects’ extensive arsenal, their recent Middle East travels and evidence that one had been in touch with people with Islamist extremist views, both in the United States and abroad, all contributed to the decision to refocus the investigation. But officials emphasized that they were unclear what set off the attack, and said they were not ready to call it terrorism/New York Times. More here.