Originally published by the Voice of America (www.voanews.com). Voice of America is funded by the US Federal Government and content it exclusively produces is in the public domain. US Says Four Recent Helicopter Downings in Iraq Result of Ground Fire --------------------------------------------------------------------- http://enews.voanews.com/t?ctl=161799C:A6F02AD83191E1608965BD608B6EAE3F9574F7DCC14957C0 Meanwhile, Iraqi police say bombings and shootings have killed at least 15 people in Baghdad Sunday The U.S. military says all four of the American helicopters that crashed in Iraq in the past two weeks appear to have been shot down. Major-General William Caldwell told reporters in Baghdad Sunday the investigation is ongoing but the military is already adjusting the way it deploys helicopters in Iraq. Smoke billows from the site of a Feb. 3 explosion in central Baghdad Twenty one U.S. military personnel and private security contractors died in the crashes. Meanwhile, Iraqi police say bombings and shootings have killed at least 15 people in Baghdad Sunday.  They include four policemen killed by a roadside bomb, and another four people killed by a car bomb at a bus station. Those attacks came one day after a truck bomb attack killed more than 130 people at a market in a mainly Shi'ite district of Baghdad. In other news, Iraqi government spokesman Ali al-Dabbagh is accusing Syria of contributing to violence in Iraq by failing to stop militants from crossing its border. The Iraqi official says half of all attacks by Sunni extremists are carried out by militants infiltrating from Syria. Syria says it is doing all it can to police the border. Some information for this report was provided by AFP, AP and Reuters. .