Story highlights The girl's age was not immediately clear; guesses vary from 10 to 18

Police says explosives on her body detonated at market, killing 20 and injuring 18

The explosives went off as she was being screened at entrance of the market

Kano, Nigeria (CNN) Explosives strapped to a girl detonated at a crowded marketplace in Nigeria, killing at least 20 people and injuring 18 others, according to police.

The police estimate differed from the local hospital's estimate, which counted 51 people with blast injuries.

The blast happened at the main entrance of the ever-crowded Monday Market, the largest in the city of Maiduguri. About ‎12:40 p.m. Saturday, the girl was stopped for screening by vigilantes who man the gates of the market, according to witnesses and rescuers.

The girl was among the dead, said Gideon Jubril, Borno state's police spokesman. Her precise age was not immediately clear.

A source with inside knowledge of security operations described her as being about 17 or 18. Abur Babakura, who was at the scene, said she appeared to be about 10.

Read More