Five others were seriously wounded, according to U.S. Central Command, which didn't provide further details. The service members were not immediately identified.
The announcement of the first U.S. casualties in the conflict came as a new poll shows that one in four Americans approve of President Donald Trump's two-day-old air war, which killed Iran's supreme leader, Ayatollah Ali Khamenei, and other top officials.
“They want to talk, and I have agreed to talk, so I will be talking to them," Trump told The Atlantic magazine in a Sunday morning interview. "They should have done it sooner. They should have given what was very practical and easy to do sooner. They waited too long.”
Meanwhile, Israel and Iran continued to trade attacks. Explosions were heard in Tehran into the afternoon.