The US military is investigating a helicopter crash in Afghanistan that killed at least 13 of its soldiers.
Poor visibility may have contributed to the crash
Three civilian contractors also died in the crash and the military says two missing soldiers, thought to have been on the flight, are presumed to be dead.
Bad weather conditions - that may have downed the helicopter - are continuing, forcing rescuers and investigators to travel by road to the crash site.
The crash was the single heaviest loss of life for US troops in Afghanistan.
The US military has lost more than 130 personnel since it invaded Afghanistan in 2001 and toppled the hardline Taleban government.
Many of the deaths in the mountainous central Asian country have been blamed on accidents.
The helicopter was on its way to a military base at Bagram, north of Kabul, when it came down near the southern city of Ghazni.
Twin-engined aircraft with two, three-bladed rotors
Used to move soldiers, weapons and supplies
Can carry 54 troops or 25,000 lbs (11,340 kg) of freight - more than its own weight
Crew of four
Foul weather and dust storms were reported in the area at the time and the US military has said it has no indication that hostile fire had hit the aircraft.
However, a spokesman for the Taleban, whose fighters have been leading an insurgency against US forces in the south of the country, said they had attacked the helicopter.
Taleban spokesmen have frequently claimed responsibility for incidents that have led to US soldiers losing their lives.
Afghan President Hamid Karzai has expressed his sadness at the crash.
"I deeply deplore this incident, which took the lives of people contributing to stability and security in Afghanistan," he said.
Some 17,000 US soldiers are based in Afghanistan, tasked with fighting insurgents, training a national army and uprooting the opium trade.