Three Czech service members with NATO's Resolute Support mission were killed Sunday in eastern Afghanistan by a suicide bomber, the U.S. military and Czech authorities said.
In addition, one American service member and two Afghan soldiers were injured.
They were on foot patrol with Afghan forces, according to NATO.
The Czech Republic's Interior Minister Jan Hamáček confirmed the deaths on Twitter, saying, the "Czech Republic has suffered a terrible loss. Our three soldiers were killed in a suicide attack while on a foot patrol with Afghan forces in Parwan province. My thoughts remain with the families and friends of our fallen [soldiers]."
The Czech Republic "had recently approved a plan to deploy 390 soldiers in Afghanistan through 2020, up from the current 230," as part of NATO's Resolute Support mission, according to The Associated Press.
"My thoughts and prayers, along with those of all of the 41 Resolute Support nations, are with the families and friends of our fallen and wounded service members, and our injured Afghan brothers and their families," U.S. Army Gen. John Nicholson, the commander of U.S. Forces-Afghanistan, said in a statement.
The Taliban claimed responsibility, Reuters reported, and claimed to have killed "eight U.S. invaders in a tactic bombing," according to a spokesperson quoted by the wire service.
The bombing happened in the area of Charakar, in the east of the country and north of Kabul, according to reports.
Separately, The Associated Press reports the Taliban attacked a district headquarters in Afghanistan's Uruzgan province Saturday, killing four Afghan soldiers, while nine Taliban fighters died in a gunfight with Afghan soldiers.
ISIS affiliates have also continued to carry out deadly attacks in Afghanistan. ISIS claimed responsibility this weekend for a Friday attack on a Shiite mosque in Afghanistan's Paktia province that killed at least 29 people and injured at least another 80 people, according to reports.
NATO describes the Resolute Support mission as "a NATO-led, non-combat mission to train, advise and assist the Afghan National Defense and Security Forces (ANDSF)." The organization says the current mission includes about 16,000 personnel.
NATO formally ended its main combat mission against the Taliban in Afghanistan in 2014.
As of almost a year ago, the U.S. military reported having 13,329 uniformed American forces in Afghanistan, but has since stopped providing troop numbers.
U.S. service member Cpl. Joseph Maciel of South Gate, Calif. was killed last month in southern Afghanistan in what the military called an "insider attack."