A powerful bomb exploded Wednesday near the office of a political party in the southern Indian city of Bangalore, injuring at least 16 people, police said.

The bomb was planted in a motorcycle parked about 100 yards from the office of the Bharatiya Janata Party in Bangalore's Malleshwaram neighborhood, said Lalrokhuma Pachau, director general of police in Karnataka state, of which Bangalore is the capital.

The injured were being treated at nearby hospitals, where doctors said the condition of two people was serious, Pachau said. Ten of the injured were policemen who were on duty near the party office, he said.

Scores of party supporters were in the building at the time of the explosion, with elections to the Karnataka assembly due to be held early next month.

Witnesses said the blast was so powerful that nearby buildings shook and window panes were shattered.

Pachau said it was too early to say what kind of explosive had been used or who was responsible for the blast.

"At this stage we cannot say what material has been used in the blast. Investigations are going on," he said.

Police cordoned off the area and forensic experts were gathering evidence from the blast site.

Three cars and several scooters were charred in the blaze that followed the blast. A police bus parked nearby was also badly damaged.

Malleshwaram is a residential area in the heart of Bangalore, India's information technology hub. Throngs of people crowded around the explosion site and police had to push them back to allow sniffer dogs and bomb experts to gather evidence.