At least 12 people have been killed and dozens others injured in two bomb blasts in the southern Indian city of Hyderabad which police have branded an act of "terrorism".
The blasts were about five minutes apart and took place in the early evening - the first going off just after 7pm local time.
The first device went off near a cinema, and as people fled the area a second went off near a bus station, in the busy district of Dilsukh Nagar.
Men, women and children were killed in the explosions, and dozens were taken to hospital with injuries.
Indian Prime Minister Manmohan Singh said: "This is a dastardly attack, the guilty will not go unpunished.
"I appeal to the public to remain calm and maintain peace."
The bombs were attached to two bicycles about 500ft apart, according to Home Minister Sushilkumar Shinde.
"This is a terror attack for sure," said Hyderabad deputy inspector Shiv Kumar, while adding there had been no claim of responsibility for the bombings.
Questions have been raised after it emerged Indian intelligence agencies received non-specific warnings of an imminent terror strike.
Hyderabad has been targeted before in 2007, when two bombs killed 42 people.
There were some reports that up to 20 people may have been killed in the latest atrocity and 54 people wounded, 35 seriously - and that bomb disposal experts were trying to defuse three more unexploded devices.
Mahesh Kumar, a 21-year-old student, was heading home when a bomb went off.
"I heard a huge sound and something hit me, I fell down, and somebody brought me to the hospital," said the student, who suffered shrapnel wounds.
Hyderabad, India's fourth most populous city of 6.8 million people, is a hub of the country's information technology industry and has a mixed population of Muslims and Hindus.
India has been on a state of alert since Mohammed Afzal Guru, a Kashmiri, was hanged in a New Delhi jail nearly two weeks ago.
Guru had been convicted of involvement in a 2001 attack on India's parliament that killed 14 people including five gunmen.
Many in Indian-ruled Kashmir do not believe Guru received a fair trial, and the secrecy with which the execution was carried out has fuelled anger in a region where anti-India sentiment runs deep.
India's other cities are now on high alert.
Police are working on the theory that the explosions were "meticulously planned by a terrorist group", said Sky's Alex Rossi, speaking from Delhi.
"The hospitals are starting to fill up with the injured, and forensic teams have arrived on the ground. They are trying to sift through the debris, look at what's left of those explosives, to try and find any clues as to who was responsible for these attacks.
"But already there are questions about why the intelligence agencies failed to stop these attacks," he added.
The last major bomb attack in India was a September 2011 blast outside the high court in New Delhi that killed 13 people.
Australia's test match series in India is due to start Friday in Chennai, with the second test taking place on March 2 in Hyderabad.
A statement from the touring side on the eve of the first fixture said officials were in talks with the Indian cricket board in the wake of the blasts, and stressed that the safety of its players was of "paramount importance".
It said the Australians had so far received "no information to suggest there is any threat to the team".
Australia refused to play any matches in the 1996 Cricket World Cup in Sri Lanka after a series of bombings there.
All international teams have refused to play in Pakistan since 2009 when gunmen attacked the Sri Lankan team in the city of Lahore.