The New York Times reports that an explosion today in northern Nigeria was the result of a suicide bombing carried out by a girl of around 10 years old. The girl, who is still unidentified, had the explosives hidden underneath her veil when she walked in to a busy market in Maiduguri, a Boko Haram stronghold. The subsequent explosion killed at least 20 people and injured many more.

The Times notes:

The terrorist group has increasingly employed women as suicide bombers, even as it has stepped up its abductions of girls across northeast Nigeria, including the kidnapping of more than 200 in the town of Chibok last April. Late last year, two women hit the Monday Market in suicide attacks, killing dozens, and in one week last summer four women carried out bombings in northern Nigeria's biggest city, Kano.

But the use of a child to kill — witnesses, police officials, a top hospital official in Maiduguri and local vigilantes all agreed that the bomber was very young — may be unprecedented in the insurgency.

It's not yet clear whether the little girl knew she was wearing an explosive. A witness told the Times, "This girl may not necessarily know she was conveying a timed bomb. The girl was torn into two halves, and half of her body was thrown across buildings by the devastating blast."

Police indicated that this was a likely indication that Boko Haram has taken a new, more violent, tactic. "It's something quite new, and it's disturbing, using these young, young girls wearing hijabs," he said. "Now, one has to be suspicious of any lady wearing a hijab — whether it's a young lady, or an old lady."

Image via Getty, December 12, 2014 Boko Haram bombing