At least five mortar rounds exploded in central Baghdad on Thursday, including two in the Green Zone, the enclave that houses Iraq's interim administration and several foreign embassies. Witnesses reported at least one person was killed and several wounded. Thick smoke rose from the sites of the Green Zone blasts, and sirens blared across the fortified area. Two U.S. Black Hawk helicopters arrived and landed within minutes of the detonations, which bore the distinctive sound of mortar strikes. A few minutes later, more shells landed on the other side of the Tigris River, sending U.S. soldiers and Iraqis running for cover. One round struck near a mobile phone office in the al-Arasat neighborhood, killing one person and wounding three, according to police Lt. Muhsin Khazim. Witnesses also reported people were wounded in the other blasts around Baghdad, but the number of casualties wasn't known. A U.S. military spokesman confirmed multiple explosions in central Baghdad between 10:15 a.m. and 10:55 a.m. (0715-0755 GMT) but had no details. Last week, a mortar attack killed four employees of a British security firm and wounded at least 12 in the Green Zone, which houses the U.S. Embassy in Baghdad.