The blast happened west of Taji, about 19 miles north of Baghdad, a US military spokesman said.
The dead soldiers were from the US 4th Infantry Division and the paramilitary Iraqi Civil Defence Corps.
Initial reports from the television network, CNN, said the Bradley, the US army's main infantry fighting vehicle, overturned and caught fire. Its gun turret was ripped apart.
The bombing mean the number of American occupation troops to have died in Iraq has reached 501 since President George Bush ordered the invasion of the country on 20 March 2003.
Before the reported incident, 343 US soldiers had been killed in action since the start of the war in March. Including non-combat deaths, the total US casualty toll stood at 496 before Saturday's reported attack.
Elsewhere, two Iraqis were killed and six captured after a sustained attack by insurgents on a border post in western Iraq, while a huge bomb was defused near the flashpoint town of Falluja, the US military said on Saturday.
Also on Saturday, the military said a US soldier died from a non-hostile gunshot wound south of Baghdad. The incident occurred on Friday evening near Diwaniyah south of Baghdad, the command said in a statement. No further details were released.
US troops from the 3rd Armoured Cavalry Regiment gave chase late on Thursday after more than 35 blasts near a frontier post in Al-Anbar province, which stretches from near Baghdad to borders with Jordan and Syria, a statement said.
Attackers then fired rocket-propelled grenades at the coalition troops who returned fire, killing two, the statement said. A search of a nearby compound led to the arrest of six men and the capture of weaponry.