Dozens of people have been killed in northern Nigeria during fierce fighting between Islamist militants and government security forces.
The Nigerian Red Cross Monday said at least 187 people died in the fighting, while another 77 were being treated for injuries.
However, one Borno state military spokesman has said reports of such death tolls are inflated.
The gunbattles began Friday in the remote fishing village of Baga, forcing thousands of residents to flee the area.
Locals say the clashes began when troops surrounded a mosque that allegedly was sheltering members of the radical Islamist sect Boko Haram.
A shootout ensued, with militants using heavy weaponry, including rocket-propelled grenades. Soldiers and local officials say the militants used civilians as human shields, while residents say soldiers deliberately set fires during the attack.
A U.S. State Department spokesman said Monday the Untied States supports the efforts of Nigerian authorities to bring the perpetrators of violence to justice, but he said they must do so while respecting human rights and protecting civilians.
The spokesman also urged Nigeria's government to address what he called "legitimate grievances" in Nigeria's north, saying if they are not addressed, then militants groups will exploit those grievances for their own purposes.
"Our response is that violent extremism requires more than just a security response. So Boko Haram exploits legitimate northern grievances to attract recruits and public sympathy. So the response should be to address some of those legitimate needs and concerns of the people in the north so that is not being exploited by this group who clearly has perpetrated some very awful violence."
Friday's battle lasted for several hours, but news of the attack did not reach the Nigerian capital until Sunday.
Authorities blame Boko Haram for dozens of deadly bombings and shootings in northern Nigeria since 2009. Human Rights Watch says the Boko Haram-related violence has killed 3,000 people, a toll that includes killings by security forces.