BAGHDAD, Iraq - A commercial helicopter contracted by the U.S. Defense Department was shot down by missile fire today north of the Iraqi capital, the Bulgarian Defense Ministry said. All nine people on board, including three Bulgarians, were killed, officials said.

"The helicopter was shot by missile fire around 2 p.m. local time," the Defense Ministry said in a statement issued in Sofia, Bulgaria. The ministry did not provide the nationalities of the six others killed.

At the Pentagon, a senior defense official said there also were six civilian contractors aboard the aircraft. The official, who spoke on condition of anonymity, said he did not know the nationalities of the six civilians or their employers.

The U.S. embassy official said the crash involved an Mi-8 helicopter chartered from Washington-based SkyLink Air and Logistic Support (USA) Inc. Calls to the company went unanswered Wednesday.