U.S. officials say an American Black Hawk helicopter with four people on board has crashed in southwestern Afghanistan.

The officials say the crash happened Thursday during bad weather and it was not known if any of the four crew members survived.

NATO coalition spokesman Lt. Commander James Williams told VOA it is “unlikely” that the helicopter was brought down by enemy fire, but said the cause of the crash is under investigation. He said there is no confirmation of the number of casualties or the nationality of those on board.

Earlier, Afghan President Hamid Karzai said he was disgusted by photos of U.S. soldiers posing with the dead bodies of insurgents and said the images highlight a need for a faster foreign withdrawal from Afghanistan.

In a statement Thursday, President Karzai said an accelerated and full transition of security responsibilities is “the only way to put an end to such painful experiences.”

He strongly condemned the U.S. soldiers' actions, saying it was “inhumane and provocative” to take and share such pictures.

The photos dating back to 2010 show members of the U.S. Army posing with the bodies of insurgents who killed themselves in suicide attacks. The Los Angeles Times published two of the 18 photographs on its website Wednesday.

According to the Times, an American soldier released the pictures to the newspaper on condition of anonymity in order to draw attention to a breakdown in leadership and discipline that he believed posed a threat to the safety of troops.

The soldier told the newspaper that virtually all the men depicted in the photos had friends who were killed or wounded by homemade bombs or suicide attacks.

Top U.S. and NATO officials responded to the release of the pictures with swift condemnation. U.S. Defense Secretary Leon Panetta said an investigation is under way and that the individuals responsible would be held accountable.

Panetta also voiced disappointment that the newspaper did not honor an official request not to publish the pictures. The U.S. defense secretary warned the material could be used to incite violence against U.S. and Afghan troops.

White House Press Secretary Jay Carney on Wednesday described the conduct depicted in the photographs as “reprehensible,” saying it does not in any way represent the standards of the U.S. military.

The commander of NATO-led forces in Afghanistan, U.S. General John Allen, also said the soldiers' actions “undermine the daily sacrifices of thousands of ISAF troops who continued to serve honorably in Afghanistan.”

Thursday, the Taliban issued a statement again asking their supporters to “get revenge from foreign forces, by attacking them across the country.”

Insurgents had launched a series of coordinated attacks earlier this week in Kabul and other eastern cities targeting Western embassies.

The U.S. ambassador to Afghanistan, Ryan Crocker, told reporters that there was “no question” the Pakistan-based Haqqani network was responsible. Pakistani observers, however, say the U.S. claims are designed to justify drone strikes in their country.