At least nine people were killed on Tuesday following a suicide bomb attack in Nigeria's northeastern state of Adamawa, one of the three states most hit by the insurgency of Boko Haram, witnesses said.The suicide bomber detonated his explosive devices outside a livestock market in Garkida, a rural community in Adamawa, Xinhua quoted Ibrahim Tanko, a trader who witnessed the attack."Some heavy gun shots followed the explosion, causing people to run helter-skelter and seek refuge," he said, adding unspecified number of people might have sustained serious injuries.Jerry Kundusi, a local lawmaker in the area, told reporters the identity of the assailants were yet known but it was believed to be a Boko Haram insurgents act.Gunmen, suspected to be Boko Haram militants, on Sunday attacked the same area of the state, killing at least one person and abducting six women, according to officials.