Residents of a Nigerian town attacked by Boko Haram criticized security forces for failing to protect them despite warnings that the Islamic militants were nearby. At least 50 bodies have been recovered, many horribly burned, in the town.

The attack on Gamboru, in remote northeastern Nigeria near the border with Cameroon, is part of the Islamic militants’ campaign of terror that included the kidnapping of teenage girls from a school, 276 of whom remain missing and believed held by Boko Haram in the vast Sambisa Forest in northeastern Nigeria.

The death toll from the Monday afternoon attack in Gamboru was initially reported by a senator to be as many as 300, but a security official said it is more likely to be around 100. Some Gamboru residents said bodies were recovered from the debris of burned shops around the town’s main market, which was the focus of the attack.

The bodies were found after the market reopened Wednesday as health workers, volunteers and traders searched for missing people, Gamboru resident Abuwar Masta said. He said most of the bodies were burned beyond recognition. Some of the victims were traders from Chad and Cameroon, he said.

The kidnapping of the schoolgirls on April 15 in the town of Chibok has sparked accusations that the Nigerian government is not doing enough to stop the militants. Boko Haram has killed more than 1,500 people so far this year as part of their campaign to impose Islamic law on Africa’s most populous nation, which has 170 million people equally divided between Christian and Muslim.

Outrage over the missing girls and the government’s failure to rescue them brought angry Nigerian protesters into the streets this week, an embarrassment for the government of President Goodluck Jonathan.

Nigeria’s military said in a statement Thursday that the armed forces are “focused on the task of rescuing the abducted girls and that the war on Boko Haram “will be effectively prosecuted.”

On Thursday, the prosecutor of the International Criminal Court, Fatou Bensouda, said acts such as the mass abduction of girls “shock the conscience of humanity” and could constitute crimes that fall within the jurisdiction of The Hague-based court.

“No stone should be left unturned to bring those responsible for such atrocious acts to justice either in Nigeria or at the ICC,” she said in a statement.

Although Boko Haram has killed thousands of people — Christians as well as Muslims — over the years in a campaign of bombings and massacres, the group’s mass abduction of schoolgirls appears to have galvanized global attention and prompted offers of security assistance from foreign countries to help rescue the girls.

The U.S. announced on Tuesday it was sending personnel and equipment to help Nigerian security forces.

U.S. Secretary of State John Kerry said Thursday that a team of U.S. officials and agents from across the government were arriving in Nigeria to help find the girls and help the Nigerian government counter threats from Boko Haram.

Jonathan confirmed that he has accepted the American assistance, which the Pentagon said Wednesday will include communications, logistics and intelligence planning, but will not include any military operations. Britain and China said Nigeria had accepted their offers of help, and France said it was sending in a “specialized team” to help with search and rescue of the girls.