U.S. officials said Friday the four people aboard an American Black Hawk helicopter that crashed in southwestern Afghanistan were likely Americans.

Military officials say all four people are believed to have died in the crash Thursday during bad weather.

Officials say the helicopter crashed in Afghanistan's Helmand province, a Taliban stronghold.

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.

Meanwhile, 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.”

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.

U.S. Defense Secretary Leon Panetta said an investigation is under way and that the individuals responsible for releasing the photographs 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.

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