Protesters march in support of the girls kidnapped by members of Boko Haram in front of the Nigerian Embassy in Washington. Reuters

Boko Haram militants in Nigeria attacked the border town of Gamboru Ngala on Monday night, killing hundreds of people, Ahmed Zanna, a Nigerian senator, and several witnesses said.

The attack took place near the town located on Nigeria’s border with Cameroon, the Associated Press and other news agencies reported. Islamic militants set shops and homes on fire and sprayed gunfire into a busy market, which was open at night while temperatures are cool in the desert region.

“My brother who was at the scene of the attack told me that the actual number of the dead cannot be ascertained, but at least they are up to 300,” Zanna said. “In fact as we spoke, he wept as a result of the high number of the dead bodies, which littered the market.”

Zanna said the militants spent 12 hours in the town armed with armored personnel carriers (APCs), improvised explosive devices (IEDs), Molotov cocktails, assault rifles and rocket propelled grenades (RPGs), ThisDay reported.

According to Zanna, Nigerian security forces stationed near the town were moved when they received intelligence reports that Boko Haram members responsible for kidnapping 276 teenage girls were in the Lake Chad area.

“It was just an hour after their withdrawal that the terrorists invaded the town, shooting everyone in sight and setting buildings on fire. So far, 200 vehicles and thousands of houses, shops and an outfit of the Nigerian Customs Service (NCS) have all been burnt,” Zanna said.

Nigerian authorities have offered an award of about $310,000 for information that could lead to the rescue of the schoolgirls kidnapped on April 14 by the terror group.

U.S. officials have prepared to send law enforcement and military support to help find the girls. This can include a “coordination cell” which would provide intelligence, investigations and hostage negotiations expertise.

"We're going to do everything we can to provide assistance to them," U.S. President Barack Obama told NBC News on Tuesday.