The Fort Hood massacre was immediately labeled by the government's primary counterterrorism center as a terrorist attack, a former top security official testified Wednesday -- even though the Defense Department would later describe the 2009 shooting in the context of "workplace violence."

"The day after the Fort Hood attack, the National Counterrorism Center entered the attack of Fort Hood as a -- in the worldwide incident terrorist database -- as a terrorist attack, the day after. ... The NCTC called it terrorism the day after the attack," Michael Leiter, the former head of the NCTC which is the government's central hub for threat analysis, testified. He spoke before the House Homeland Security Committee.

Leiter, along with other witnesses, were part of an oversight hearing on the April Boston Marathon bombing, which killed three, and the Fort Hood shooting, which left 13 dead and wounded more than 40 others.

Fox News was first to report in December 2011, based on a letter from the Defense Department to Senate Homeland Security Committee leaders Sens. Joe Lieberman and Susan Collins, whose committee was investigating Fort Hood, that the shooting and "the threat of violent Islamist extremism" was seen in "the context of a broader threat of workplace violence."

The former Republican mayor of New York City, testifying at Wednesday's hearing, said the classification was insulting to the victims and dangerous.

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"I think it is exceedingly damaging to engage in this fiction that the attack at Fort Hood was workplace violence," Rudolph Giuliani testified.

He was joined by Texas Democratic Rep. Sheila Jackson Lee, who along with committee Chairman Mike McCaul, R-Texas and Republican New York Rep. Peter King wants those killed and injured at Fort Hood to receive the Purple Heart -- which is impossible under a workplace violence designation.

"I would indicate to you, mayor, that many civilians were impacted at Fort Hood and I champion the cause that it was in no way workplace violence," Jackson Lee said.

On the Boston attack, McCaul also said the FBI refused to provide a witness who could explain the apparent failure of the bureau to share information with the Boston police about the FBI investigation into Tamerlan Tsarnaev after a tip from the Russian government in 2011 that Tamerlan was believed to be a follower of radical Islam.

"Unfortunately the FBI has refused to appear and continues to refuse this committees appropriate request for information and documents crucial to our investigation into what happened in Boston," McCaul said.

Asked for an explanation, an FBI spokesman said McCaul had met with the senior FBI agent in Boston a few weeks ago to answer his questions, and to inspect the bombing site, adding timing was a factor in the FBI's decision not to provide a witness because Boston suspect Dzhokhar Tsarnaev has his first court appearance Wednesday.

"We have an obligation to protect the integrity of the judicial process while it is ongoing. This involves ensuring both the government's ability to conduct a successful prosecution as well as the rights of all parties involved including the defendant who, as it turns out, has a court appearance on the same day as this hearing," the FBI statement said.