(Adds claim of responsibility in para 5) BAGHDAD, Feb 21 (Reuters) - Insurgents shot down a U.S. military helicopter with nine people on board north of Baghdad on Wednesday but no one was killed, the military said. It was the eighth downing of a helicopter in Iraq in a month. A military spokeswoman said it appeared the Black Hawk helicopter had been brought down by small arms fire and rocket-propelled grenades. The U.S. military said in an earlier statement that all nine people on board were evacuated and there were no serious injuries. The Mujahideen Army claimed responsibility for bringing down the helicopter in a brief Internet posting. Iraqi police captain Mahmoud al-Mashhadani said he saw some type of projectile hitting the helicopter before it came down in a rural area known as the Line, 30 km (18 miles) north of Baghdad. "I saw a ball of fire hitting the aircraft and smoke coming out of the helicopter as it came down," Mashhadani told Reuters. Major-General William Caldwell, the chief U.S. military spokesman in Iraq, told an earlier news conference the helicopter made a "hard landing", without giving details. Before Wednesday's incident, insurgents had shot down seven helicopters since Jan. 20, killing 28 people, mainly American soldiers. Five of those helicopters were U.S. military aircraft and two belonged to a private American security firm. The incidents have raised questions about whether insurgents are using new tactics, such as studying aircraft flight patterns, or have acquired sophisticated weaponry. U.S. commanders have said one reason they believe insurgents have focused on helicopters was to try to undermine a security crackdown in Baghdad that began last week.
