Complex sentence: No terrorist group claimed responsibilty for the explosions immediately, but multiple sources noted that Islamic extremist group Boko Haram may be responsible for the attack as the blasts have similarities to previous Boko Haram attacks.
Split into simpler sentences: No terrorist group claimed responsibilty for the explosions immediately. But multiple sources noted that Islamic extremist group, Boko Haram, may be responsible for the attack as the blasts have similarities to previous Boko Haram attacks.