Suspected Maoist militants attacked a group of trucks jammed with passengers Tuesday in central India, killing 23 people and injuring 33, police said.

The militants blew up one truck and set fire to two others after stopping them near the town of Darbhaguda in rural Chhattisgarh state, said Girdhari Naik, a state inspector general of police.

Most of the casualties were believed to be in the truck that was blown up, Naik said.

The attack, about 750 miles southeast of New Delhi, came just one day before President Bush arrives in India for a four-day visit. Fearing militants will time attacks to coincide with the visit, India has dramatically increased security in some parts of the country in recent days, particularly the volatile Himalayan region of Kashmir.

In 2000, 35 Sikh villagers were massacred in Kashmir by unidentified assailants on the eve of a visit by then-President Clinton.

The region where the blast occurred Tuesday has been the scene of a number of recent bloody attacks by the militants, who claim to be inspired by Chinese revolutionary Mao Zedong and say they are fighting to defend the rights of poor people. They are active in several eastern and central Indian states.