Three groups of students freed in Nigeria in 24-hour period

Some freed students from the Salihu Tanko Islamic School (AP Photo)

Authorities in northern Nigeria announced three separate groups of kidnapped students were freed within a 24-hour period, prompting speculation that large ransoms had been paid to the gunmen blamed for a spate of recent abductions.

Among those now free are some of the youngest children ever taken hostage in Nigeria, a group of 90 pupils who had spent three months in captivity.