A 10-year-old girl blew herself up Friday in Damaturu, Nigeria, killing at least 12 other people who were worshipping in an open-air praying area for the Eid al-Fitr holiday.

The girl, who has still yet to be identified, was accompanying an elderly woman, who was also strapped with an explosive device. Both of the suicide bombers detonated their bombs as people were lining up for a security check.

"Four persons died in the first explosion and seven people were injured. While in the second explosion, five people lost their lives and 11 people were wounded," a spokesman for the Nigerian military told Reuters.

A third young bomber was reported to have detonated another bomb in a nearby mosque later, raising the death toll to 13, The Inquisitr learned.

No one has claimed responsibility for the attack, although the nature and manner by which it was carried out were attributed to the terrorist activities of the dreaded Boko Haram group. Boko Haram has been increasingly employing young people as suicide bombers since it allied itself with ISIS. ISIS has been abducting children, training them as bomb makers, suicide bombers and human shield against U.S.-led airstrikes, HNGN reported in February.

Boko Haram, which has now killed thousands of people and displaced at least a million Nigerians, has been the target of the government's military operation since May, according to Al Jazeera. The group has also increased its militant activities, killing hundreds of people in a string of raids and bombings. At least 50 people were already killed on Thursday in a blast at a market in Gombe, a city 200 km away from Damaturu.

Recently installed Nigerian President Muhammadu Buhari will meet President Barack Obama on Monday and is expected to discuss his government's drive to defeat Boko Haram, which identifies itself as an ally of Islamic extremist group ISIS, CNN reported. The group controls a swathe of territory that is as large as Belgium. Nigeria has begun to successfully flush them out of the area in cooperation with its neighboring Chad, Niger and Cameroon, according to Al Jazeera.