Abuja, May 18 : Nigerian President Muhammadu Buhari has expressed sadness over an attack by suspected gunmen on a convoy of the US consulate in the country's southern state of Anambra, killing two local employees and two policemen. The gunmen laid an ambush for the convoy and opened fire in the Ogbaru local government area of Anambra Tuesday, fleeing the spot before the arrival of security operatives, according to an earlier statement by the police on Wednesday. Buhari said in a statement on Wednesday that he was "very sad" hearing about the attack, and called on security agencies to fish out "the perpetrators of the dastardly act". In a separate statement, Tochukwu Ikenga, spokesman for the police in Anambra, said no US citizen was on the trip, Xinhua news agency reported. Ikenga added that the bodies of the victims were set ablaze, together with their vehicles, by the gunmen. /IANS