Police say at least 20 people have been killed in an explosion set off by Maoist rebels in central India's Chattisgarh state.
Police say the rebels blew up a vehicle filled with anti-Maoist activists Tuesday.
The killings come on the eve of President Bush's visit to India.
Maoist rebels say they are fighting for the rights of poor peasants and landless workers. They have battled authorities for decades.
Some information for this report was provided by AFP and Reuters.