|Forensic police inspect a security officer's hat at the scene of the blast [AFP]
At least 10 people were wounded when two bombs exploded on Saturday outside a packed Indian Premier League cricket stadium in the southern city of Bangalore, stirring fears about more militant attacks.
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 US State Department issued a travel alert which said: "The US 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 between Mumbai Indians and the home team Bangalore Royal Challengers.
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, featuring top foreign players started an hour late after police secured the area and assured players of proper security at Chinnaswamy Stadium.
The Bangalore team includes Kevin Pietersen from England, Jacques Kallis and Dale Steyn from South Africa, while Mumbai have star batsman Sachin Tendulkar and Kieron Pollard from West Indies in their playing 11.
Initial investigations show the explosives used in the blasts were locally made and of low intensity, MR Poojar, the city's additional police commissioner, told The Associated Press news agency.
The International Cricket Council said it was too early to comment on the attack.
Bangalore is set to host four games during the World Cup starting next February.
Pakistan lost co-host rights for the World Cup a year ago after terrorists attacked the Sri Lanka team convoy in Lahore, killing six police officers and a driver.
Sports venues in India have faced tight security amid fears that Islamist radical groups may target them, with last year's IPL being held in South Africa.