The explosion, suspected to have been triggered by an improvised explosive device (IED) reportedly went off at about 10pm local time, targeting the office of the wife of a former Secretary to the State government, Pastor Osagie Ize-Iyamu.
One of the security men guarding the premises reportedly escaped death by the whiskers.
Eye-witnesses said a large section of the building was destroyed by the powerful explosion and the fire which ensued.
Police sources said officers of the anti-bomb squad had cordoned off the area and would begin investigating the attack.
Ize-Iyamu, a former national officer of Governor Oshiomhole’s former party, Action Congress of Nigeria (ACN), had dumped the party for Peoples Democratic Party (PDP).
Since the defection, the former ACN chieftain had become one of the fiercest critics of the Oshiomhole administration.