Thousands of members of the Palestinian security forces began casting ballots for parliamentary candidates Saturday in the official start of voting for this week's Palestinian elections. Some 58,000 security personnel were expected to participate in special early voting in the coming days - ahead of Wednesday's election - to allow them to take up positions on election day. The mass deployment scheduled Wednesday is to prevent political violence. The ruling Fatah Party faces a stiff challenge from the Islamic group Hamas, which is participating in a legislative vote for the first time. A poll released Friday put the two movements in a dead heat. Voting opened Saturday shortly after 7 a.m.