KABUL, Afghanistan (CNN) — Four Americans were killed in an apparent suicide bomb attack early Saturday at Bagram Airfield, the largest US base in Afghanistan, US Defense Secretary Ash Carter said.
Two of those killed were service members, and two were contractors, he said, adding he was “deeply saddened” by the news.
The explosion also wounded 16 other US service members and one Polish soldier participating in the NATO mission, Carter said in a statement.
The Taliban claimed responsibility in a tweet praising the “strong attack” on Bagram Airfield.
In a statement, Taliban spokesman Zabihullah Mujahid said a suicide bomber had targeted “a sports ground where more than 100 military officers, important people and soldiers were busy exercising.”
The attack on the airfield had been planned for four months, he said.
A NATO coalition official told CNN that the bomber, who is presumed dead, detonated the suicide bomb vest on a sidewalk near where people were gathering for a run.
The base was under lockdown, and additional security measures were instituted at all other locations in Afghanistan for the United States and coalition allies, the official said.
Carter offered his condolences to the families of those killed and said the injured were getting the best possible care.
“Force protection is always a top priority for us in Afghanistan, and we will investigate this tragedy to determine any steps we can take to improve it,” he said. “For those who carried out this attack, my message is simple. We will not be deterred in our mission to protect our homeland and help Afghanistan secure its own future.”