A suicide bombing in eastern Afghanistan has killed three members of NATO's Resolute Support force, the U.S. military said.
"Three Resolute Support service members were killed by a suicide bomber during a combined, dismounted patrol with Afghan forces in eastern Afghanistan," the August 5 statement said.
The attack, which was claimed by the Taliban, is being investigated.
A U.S. soldier and two Afghan troops were also wounded in the blast, which targeted a foot patrol, the statement said, without specifying the nationalities of the soldiers who were killed.
The Czech military issued a statement saying the three victims were all Czech service members.
It said the attack took place early on August 5 near the Bagram military base in the province of Parwan.
The victims have not been identified. A statement from the military said the families of the victims had been informed and Defense Minister Lubomir Metnar had offered his condolences.
The Czech government has recently approved a plan to deploy 390 troops in Afghanistan through 2020, up from the current 230, as part of the NATO-led Resolute Support mission.
U.S. Army General John Nicholson, commander of Resolute Support and U.S. Forces-Afghanistan, said in a statement, "Their sacrifice will endure in both our hearts and history and further strengthen our resolve."
NATO formally concluded its combat mission in Afghanistan in 2014, but thousands of troops are still providing support and training to the Afghan National Army, and carrying out counterterrorism missions.
Eastern Afghanistan remains one of the deadliest areas for the U.S. military since its main combat operation against the Taliban ended in 2014.
Last month a U.S. soldier was killed and two others wounded in an "apparent insider attack" in southern Afghanistan, NATO said.
Meanwhile, hundreds of mourners have buried the victims of a twin suicide attack on a Shi'ite mosque in eastern Afghanistan, as the death toll rose to 35, officials said.
Two suicide bombers dressed as women struck a Shi'ite mosque in Gardez, capital of Paktia Province, on August 3 as it was crowded with worshippers for weekly prayers.