Two female suicide bombers—one as young as 11—blew themselves up at a crowded mobile phone market in the city of Kano, in northeast Nigeria, killing at least 15 people, a day after a bomb blast elsewhere in the country left more than 30 dead.

One of the bombers was said to be just 11 years old, Agence France-Press reports, and the other 18:

The Islamist terror group Boko Haram has previously used young girls as human bombs in its six-year insurgency in north-east Nigeria, which has left at least 17,000 dead and made more than 2.6 million homeless.

In July 2014, Kano was hit four times in the space of a week by a spate of young female suicide bombers, whom experts say are unlikely to be willing participants to the carnage.

Kano police spokesman Musa Magaji Majia said that the girls, both wearing the hijab, were dropped off by a minibus at the Farm Center GSM market.

“One went inside the market, the other stayed outside. Then they exploded, killing themselves and others nearby,” he told AFP. “The victims were taken to hospital and it was later confirmed that 15 people died, not including the suicide bombers.”

Both Tuesday’s and Wednesday’s bombings resemble earlier attacks by Boko Haram, although the Islamist militant group’s responsibility has not yet been determined

President Muhammadu Buhari, who called the attacks “barbaric” and “cowardly,” has given his military until next month to defeat Boko Haram. “Nigeria’s reinvigorated, well-equipped and well-motivated armed forces and security agencies [will] overcome Boko Haram very soon,” he said.

Photo via AP Images. Contact the author of this post: brendan.oconnor@gawker.com.