The military said the crash, which is under investigation, "does not appear to be a result of enemy activity".
Four of the airmen were assigned to the 106th Rescue Wing at the Francis S. Gabreski Air National Guard Base, N.Y. He was assigned to the 38th Rescue Squadron at Moody Air Force Base, Georgia.
Two US officials, speaking on condition of anonymity and citing initial reports, said on Thursday the aircraft crashed near al-Qaim, a town in Anbar province close to the Syrian border.
Russian Federation to expel British diplomats in retaliatory move
Moscow has denied any involvement in the attempted assassination of Skripal, a former Russian spy turned double agent for the UK. Mr Basu said investigators were making good progress but further work could take "months".
"Lt. Raguso and Fire Marshal Zanetis bravely wore two uniforms in their extraordinary lives of service - as New York City Firefighters and as members of the United States Armed Forces", Fire Commissioner Daniel Nigro said Friday.
The names of those killed will be released after next of kin have been notified, the statement added. He previously served in Afghanistan as a munitions system specialist with the 106th Maintenance Group, and completed missions in Texas and the Caribbean following Hurricanes Harvey and Irma a year ago. He also previously deployed to Iraq and Afghanistan.
-Capt. Christopher T. Zanetis, 37, of Long Island City, New York. "I extend our deepest condolences and prayers to family, friends and fellow airmen during this hard time". According to the statement, he recently joined the law firm of Debevoise & Plimpton in New York City as an associate. The 37-year-old was from Center Moriches. "They did rescue work here in the United States during the hurricanes just previous year". He previously deployed to Iraq as a fire protection specialist with the 106th Civil Engineering Squadron, twice to Afghanistan with the 101st, once to the Horn of Africa, and to Texas and the Caribbean for Hurricanes Harvey and Irma.
Russian Federation to expel United Kingdom diplomats in spy row
The source of the nerve agent - which Britain says is Soviet-made Novichok - is unclear, as is the way it was administered. May says the March 4 attack on Sergei Skripal is a "flagrant breach of worldwide law and the chemical weapons convention".
He posted: 'Our thoughts and prayers go out to the families and loved ones of the courageous troops lost in the helicopter crash on the Iraq-Syria border yesterday.
'This tragedy reminds us of the risks our men and women face every day in service of our nations'.
Thousands march in San Francisco's St. Patrick's Day Parade
Elsewhere around 300 iconic landmarks and sites in 50 different countries took part in this year's so-called Global greening. In Northern Ireland, the day will be marked with a carnival parade and free concert at Custom House Square.