Iraqi officials say at least two civilians have been killed and four others wounded in a roadside bombing in central Baghdad. Police and hospital officials say the blast was targeting a minibus and those killed were passengers. Wednesday's blast comes Iraqi lawmakers are expected to vote on a US-Iraqi security pact that would allow American forces to stay in the country for three more years. Proponents of the agreement argue that the Americans are still needed to maintain recent security gains. The explosion occurred in the Firdous Square area where thousands of followers of anti-US cleric Muqtada al-Sadr rallied last week to protest the deal.