There was no immediate US confirmation of the air raid on the town late on Thursday, but CNN reported that a military operation against Samarra was under way.
"We have received four seriously wounded people. They are a child, a woman and two men," said Dr Khalid Ahmad at Samarra hospital.
Iraqi police said the air strike came on the heels of clashes between fighters and US soldiers backed by tanks.
Two houses were destroyed in the northern district of Kadissia, said Colonel Muhammad Fadhil.
The latest US strike on Samarra follows one on 23 September in which three people, including an old woman, were killed.
US troops had sealed off the city and attacked it from the air then, endangering a fragile truce between Iraqi fighters and US forces.