At least 33 people were killed and nearly 135 injured in a series of 12 bombings that rocked India's north-eastern state of Assam on Thursday, officials and news reports said, reproted dpa.
Officials said there were 12 blasts, the first at 11:20 am (0550 GMT). Five took place in the state capital Guwahati, three in Barpeta district, three in Kokrajhar district and another in Bongaigaon district, all in western Assam, the IANS news agency reported.
"According to the information we have, 33 people died in the blasts and 135 were injured, 10 victims were in Guwahati alone," an official from the police control room in Guwahati said by telephone.
Nearly 30 of those injured in what were believed to be high-intensity explosions, were in critical condition.
Television footage showed thick black smoke billowing from destroyed shops and mangled vehicles as people screamed and ran in panic.
The blasts took place in Guwahati's busy markets such as Fancy Bazar, Pan Bazar and the district court complex, where heavy security is generally deployed.
"The area was teeming with people, office goers, shoppers and vendors when a very big explosion took place," Arindam Das, a witness at the blast scene in Ganeshguri area in Guwahati told the IANS.
"I saw at least six dead bodies, while more than 30 people were lying on the ground and bleeding," Das said.
The Indian Prime Minister Manmohan Singh condemned the blasts and appealed to Indians to fight terrorism united as a nation.
No militant or terrorist group claimed responsibility for the attacks.
Several militant outfits with demands ranging from autonomy to secession are active in the north-eastern Indian state.
Besides suspecting the United Liberation Front of Asom (ULFA), the major separatist group, police are also suspecting Muslim militant groups.
Earlier this month, two people were killed in four bombings that local police blamed on Muslim militants based in neighbouring Bangladesh.
More than 20,000 people have been killed in violence in Assam since 1979.
Indian security agencies said they were investigating which militant organization was behind the attacks.
"We cannot say anything about who is behind the attacks until we get the complete investigation report," junior Home Minister Sri Prakash Jaiswal told reporters.
"Assam has been a disturbed state and has witnessed such incidents every one or two months over the last 30 years," he said.
The Assam government meanwhile believes the banned ULFA could have perpetrated the bombings.
"It is very early to make a conclusion but ULFA has a history of triggering serial blasts," Assam's Health Minister Himanta Biswa Sarma said.