Borno state senator Ahmed Khalifa Zanna told Sky News hundreds of people were reported to have been killed in the northeastern Nigerian town of Gamboru Ngala by armed men believed to be from Boko Haram.
He said the suspected militants opened fire on residents, before burning down numerous shops and businesses in the town near the Cameroon border.
Mr Zanna is also reported as saying the town was left unguarded after soldiers were moved to join the hunt for the 276 girls who went missing from a boarding school in the village of Chibok in Borno state, north Nigeria, on April 14.
A further 11 girls, aged 12 to 15, were taken from the northeastern village of Warabe on Tuesday.
Boko Haram's leader Abubakar Shekau claimed responsibility for the mass abduction in a video, in which he also threatened to sell the girls "on the market".
It was not immediately clear whether the video was recorded before or after reports emerged that some girls had been trafficked into neighbouring Chad and Cameroon.
Mr Zanna told Sky News he did not believe any of the girls have yet been sold, but had heard information that some have been passed to Cameroon for marriage.
Relatives and campaigners have staged regular protests and launched a social media appeal, under the banner "Bring Back Our Girls," which calls on the government to do more.
The British Government said it would send a small team of experts, possibly including military officers, to assist with the search.
The group will concentrate on planning, co-ordination and advice rather than taking in part in operations to free the girls on the ground.
Prime Minister David Cameron's spokesman said the team would be in the country as soon as possible, although did not specify how many people it would involve.
In a speech to parliament Mr Cameron earlier condemned the kidnapping as "an act of pure evil."
He said: "This is not just a Nigerian issue; it is a global issue.
"There are extreme Islamists around our world who are against education, against progress, against equality and we must fight them and take them on wherever they are."
The UK team will join fewer than 10 US military troops due to be sent to the country over the next few days.The Pentagon said they would be part of a larger US assistance team, including State Department and Justice Department personnel, who would help with intelligence, communications and logistics.
Spokesman Col. Steve Warren made clear the US had no plans to launch a military operation.
US President Barack Obama has pledged to do "everything we can" to help rescue the youngsters.
Boko Haram, whose name means 'Western education is sinful,' has fought a five-year insurgency against the Nigerian government and hopes to carve out an Islamic state in northern Nigeria.
Nigerian police have announced a 50m Nigerian naira (£182,000) reward for credible information leading to the location and rescue of the female students.
