BANGALORE At least 10 people were wounded when two bombs exploded on Saturday outside a packed cricket stadium in Bangalore, stirring fears about more militant attacks, police said.
Police said a third bomb was found and defused outside the stadium, and preliminary investigations showed that a timer device may have been used.
"It was a huge noise and people started to run. We were really scared," Arun Kumar, a witness, told television channels.
The explosions came a day after the U.S. State Department issued a travel alert in which it said: "The U.S. government continues to receive information that terrorist groups may be planning attacks in India".
India said on Saturday it was further tightening security before the October Commonwealth Games after the United States issued its warning about possible militant attacks on hotels and markets in India.
Several cricket-playing countries had warned their players in advance about participating in the Indian Premier League (IPL) about security threats in India.
The blasts blew off portions of an outer wall of the stadium, packed with people who had come to watch a match in the popular tournament.
Bangalore police commissioner Shankar Bidari said the two bombs that exploded may have been hidden behind a plastic board.
"It is a minor bomb blast, but investigations are in full swing to find out who is responsible," Bidari told reporters.
The Twenty20 cricket match between Mumbai Indians and the home team Bangalore Royal Challengers, featuring top foreign players started an hour late at (1130 GMT) after police secured the area and assured players of proper security.
The Bangalore team includes Kevin Pietersen from England, Jacques Kallis and Dale Steyn from South Africa, while Mumbai has star batsman Sachin Tendulkar and Kieron Pollard from West Indies in their playing 11.
Home Ministry officials said cities had been asked to bolster security in key installations after the Bangalore blast, the second bomb attack since the 2008 Mumbai raid in which 166 people were killed in a three day carnage.
In February, a powerful blast ripped through a restaurant in Pune, killing 17 people. India has blamed the Indian Mujahideen, a homegrown militant group with links to militants in Pakistan, for the Pune attack.
The Congress-led government is under increasing pressure from the opposition for failing to tackle issues such as security and food inflation as it heads into eight key state polls over the next two years.
India remains jittery about a perceived threat of Islamist attacks from Pakistani territory. It accuses its neighbour of failing to act against militant groups which have threatened to disrupt the cricket tournament and the Commonwealth Games.
New Delhi has called a pause in peace talks with Pakistan since the 2008 Mumbai attacks by Pakistani-based militant group Lashkar-e-Taiba. It wants "credible steps" by Islamabad to bring the suspects to justice.
There was no immediate claim of responsibility for the Bangalore blast. Police commissioner Bidari said forensic science experts were scouring the area for clues.
In 2008, one woman was killed and several wounded in several low-intensity blasts in Bangalore, which were blamed on homegrown militant groups from southern India.
(Writing by Bappa Majumdar; editing by Michael Roddy)