21 dead in shootout in Nigerian capital

Detainees suspected of being members of Islamist militant group Boko Haram overpowered their guards at a prison near Nigeria's presidential villa in Abuja, seizing a rifle and triggering a gun battle that killed 21 people, security officials said. The prisoners struck on Sunday as the guards from Nigeria's State Security Service (SSS) came in to feed them at their headquarters' prison near the residence of President Goodluck Jonathan, SSS spokeswoman Marilyn Ogar said.
Background:
Shootout in Nigerian capital during attempted jail break kills 21 [Reuters]
Nigeria 'attempted jailbreak' leaves more than 20 dead [BBC]