This overturned bus was carrying security forces on their way to polling booths when it came under attack.
At least seven soldiers and two civilains were killed.
SOT Rakesh Kumar, security official
"Suddenly the vehicle was in the air. Some peopel fell out, others were stuck inside. We went into offensive mode and starting firing. They wanted to kill us and loot our weapons, but we didn't let them succeed."
Much of the first day of voting is taking place in states where a violent peasant insurgency, inspired by the teachings of Chairman Mao, has taken deep root.
Maoist rebels don't believe in parliamentary democracy and have threatened to cut the hands off people who vote.
In other incidents five election officials were killed in a landmine blast and several polling booths came under attack, despite tight security.
Rebels burned some electronic voting machines and blocked roads to prevent people voting.
There have also been reports of gun battles.
The Indian Prime Minister Manmohan Singh has called the four-decade old Maoist insurgency the country's biggest internal security challenge.