bicyles took place in the peak hour at two sites 100 metres apart outside a roadside eatery near Konark and Venkatadiri theatres in the area located on the Hyderabad-Vijaywada national highway in Cyberabad police limits.
A woman was among the 12 dead, said state DGP Dinesh Reddy, who said it was "definitely the handiwork of a terrorist network." Reddy said IEDs were used in the attack.
Union home secretary RK Singh said the near two simultaneous very powerful blasts indicate that it was a "terror attack".
Andhra Pradesh chief minister N Kirankumar Reddy said five-six of the injured were serious.
The twin blasts, described as dastardly by Prime Minister Manmohan Singh who announced a Rs. two lakh exgratia to the kin of each of the victims, triggered a stampede-like situation with people trying to scamper for safety as it left a bloody trail.
The scene wore a gory look with severed body parts lying around. Footwear and various other objects were also seen indicating the desperation of the victims and the injured to flee the spot.
The Dilsukhnagar area is thickly populated and traffic jams are routine in the evenings with officegoers and students rushing home. Large numbers of people wait at the numerous bus shelters, eateries and shops in the area.
Eight people were killed in the first blast that took place at 6.58 PM near Konark theatre and three in the second that followed three minutes later.
Shinde said two bombs were placed within a distance of 100 to 150 metres and placed in two bicycles.
The injured have been rushed to various hospitals by ambulances and police and bomb disposal squads swung into action and began searches.
Shinde, who is likely to visit Hyderabad tomorrow, spoke of some intelligence inputs for the last two days which was shared with all the states but there was no specific information "like this", referring to the terror strike.
Official sources said a general alert was issued for two consecutive days from February 19 to all major cities suggesting a possible attack by Pakistani-based terror groups to avenge the hangings of Parliament attack convict Afzal Guru and Mumbai attack convict Ajmal Kasab.
Prime Minister Manmohan Singh condemned the blasts, saying those behind the dastardly act will not go unpunished.
A team of National Security Guards(NSG) was being rushed to Hyderabad.
The previous major attack in Hyderabad was on August 25, 2007 when two blasts took place almost simultaneously in which 42 people were killed. The first blast was in Lumbini amusement park followed by another at an eating joint.
In the same year, there was a blast at the famous Mecca Masjid in which nine people were killed.
Union home secretary R K Singh said a NSG team headed for Hyderabad from Delhi by a BSF aircraft. A team of NIA hub stationed in Hyderabad has also rushed to the spot.
Singh said no group has taken responsibility yet.
There were reports that the bomb blast could be heard two to three kms away from the site of the explosion.
Sources in the state-run Osmania General Hospital said of the around 30 injured people admitted some of them were in a serious condition. They said three bodies were received brought dead.
Official sources said 14 blast victims were admitted to private Yashoda hospital at Malakpet. In another private hospital, 18 injured persons were admitted.
S A Huda, Additional DGP (law and order), said the bomb blasts occurred at two places both in the Dilsukhnagar area falling within the Cyberabad Commissionerate.
Heart rending scenes were seen at the hospital as blood soaked injured persons, some of them grievously, were being treated amid wails of their relatives.
Chief Minister N Kiran Kumar Reddy and Home Minister P Sabita Reddy also rushed to the spot. The chief minister described the attack as an "act of cowards".
The Dilsukhnagar area witnessed a blast in 2002 near a famous Saibaba temple in which two persons were killed and over 20 injured.
PM says 'dastardly attack'
Prime Minister Manmohan Singh on Thursday decsribed the twin blasts in Hyderabad as an "dastardly attack" and said the guilty should not "go unpunished."
"This is a dastardly attack, the guilty will not go unpunished," a tweet from the Prime Minister's Office (PMO) quoted Manmohan Singh as saying of of the two blasts that killed at least 10 people and injured 50.
The PMO also said that the prime minister "strongly condemned" the bomb blasts.
"I appeal to the public to remain calm and maintain peace."
"PM also directed the central agencies to extend all possible help to Andhra Pradesh state authorities in relief operations," the tweet said.
BJP condoles loss of lives
BJP President Rajnath Singh on Thursday condoled the lost of lives in Hyderabad blasts and demanded that the government conduct a thorough probe into the incident.
"I express my condolences to the family members of those killed in the blast. This is a condemnable incident. I hope the government will take appropriate action to provide immediate and adequate relief to those injured in the blast," Singh said.
Singh also demanded that a thorough probe be ordered to find out the culprits and bring them to book.
He also said government should take steps to prevent recurrence of such incidents in future.
'NIA, NSG teams reached Hyderabad'
Elite teams of the National Investigation Agency (NIA) and the National Security Guard (NSG) will be flying to Hyderabad, which has been rocked by twin blasts that killed 10 people and injured 50, an official said.
"We have a news of two blasts. We have spoken to state chief secretary, DGP (director general of police) and governor (ESL Narasimhan)," home secretary RK Singh told reporters in New Delhi.
"Ten people have died and 50 have been injured in the blasts," he said.
He said the state police chief is reaching the blast site, which has been cordoned off.
"Our NIA team is also reaching as it has a hub there. The NIA officials are there at the site. Our IG NIA is also going from here. The post blast investigating team of NSG is also going," he told reporters,
The two teams will fly at 9.30 pm in a Border Security Force plane, he added.
The near-simultaneous blasts occurred near two theatres in Dilsukhnagar, a busy commercial area in the southern part of city, about 15 km from downtown.
Police have not yet confirmed either the cause of the explosions or the number of casualties.
The first blast occurred around 7 pm near a tiffin centre opposite Venkatadri Theatre and the second near Konark Theatre. Both the theatres are about 500 meters from each other.
High alert across Andhra Pradesh
Police sounded high alert in Hyderabad and other cities in Andhra Pradesh after two blasts killed over 10 people in Hyderabad and injured scores of others.
Police with dog squads began search operations in several busy market areas in Hyderabad and its twin city Secunderabad to foil any explosives.
Security was beefed up at Rajiv Gandhi International Airport at Shamshabad, state secretariat, Charminar and other vital installations, a police official said.
An alert was also sounded in coastal city of Visakhapatnam, temple town of Tirupati and other major towns across the state.
With inputs from PTI, AFP, IANS)
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People search for survivors of bomb blast at Dilsukhnagar in Hyderabad. PTI photo