Gen. Dunford said the American soldiers werer part of a regular October 4 patrol, but suddenly found themselves in a firefight with attackers who have pledged their support for the Islamic State.
"They did not expect resistance on this particular patrol," Dunford said. "Again, what happened will be the subject of the investigation.
The general said the current rules of engagement for U.S. forces in Niger are that they go out on patrols with friendly forces only "when the chances of enemy contact are unlikely."
"They were equipped with machine guns and small arms," Dunford said, adding that the attack on the American and Niger force was done with small arms, machine guns and rocket propelled grenades.
The General said five Niger soldiers were killed in the same incident, as he vowed to get all of the details of what happened, and deliver those facts not only to the Congress - but to the families of the soldiers as well.
After a week of increasingly acidic exchanges between the the family of one soldier who died in the event and top officials at the White House - including the President - Gen. Dunford's tone was decidedly more measured, as he repeatedly told reporters that questions about the details of the firefight were entirely 'fair.'
At one point, the General was asked to comment on the remarks of White House Chief of Staff - and former General - John Kelly; Dunford claimed he didn't know enough to say anything on the matter.
In the Congress, black lawmakers took to the House floor on Monday night, expressing their support for the family of Sgt. La David Johnson, and for Rep. Frederica Wilson (D-FL), who found herself targeted repeatedly in recent days by President Donald Trump.
"How their loss - through no fault of their own - turned into an ugly name calling, I am baffled," said Rep. Sheila Jackson Lee (D-TX).
"I want the White House to know this, I and the members of the Congressional Black Caucus will not be silent," said Rep. James Clyburn (D-SC).