NEW DELHI -- The death toll from Thursday's explosions in Hyderabad, India, rose on Friday to 16 people, as new information about India's deadliest bombing since 2011 suggested the attacks had been long planned, raising questions about whether they could have been prevented.
Two days before the blasts, national intelligence sources warned that there might be terrorist activity in Hyderabad and other Indian cities including Bangalore and Coimbatore, the Home Ministry reported on Friday. Four days before, wires were cut to security cameras in the area, NDTV reported, citing police officials. The cameras not been repaired, even though the traffic police knew they were not working.
Residents of the city are set to demonstrate on Sunday. They plan to block roads, including the main highway to Bangalore.
The blasts went off within about 150 yards of each other near a crowded bus stop in the neighborhood of Dilsukh Nagar, an area packed with shops, restaurants, theaters and a huge produce market. A senior police officer said that iron nails were found at both sites.
An Oct. 26 Delhi Police news release about the arrest of four people in connection with explosions in Pune two months earlier mentioned the Dilsukh Nagar neighborhood as a potential target. It said one of the militants arrested in the 2012 blasts, Imran Khan, had done reconnaissance of the Hyderabad neighborhood "on a motorcycle" with an accomplice.
The news release tied the 2012 attack to Riyaz Bhatkal, the accused leader of an Islamic radical group called the Indian Mujahedeen.
Officials were investigating whether the attack was connected to the Feb. 9 execution of a Kashmiri militant accused of a deadly 2001 assault on India's Parliament. The execution, conducted in secret, set off unrest in Kashmir and led the government to impose a curfew in the Kashmir Valley.
Hyderabad, with a population of more than six million, has a fairly vibrant Muslim community and has been the site of attacks before.
The city was the target of twin synchronized bombings in 2007 that took the lives of 42 people at popular gathering spots. In the hours after that blast, the police found and defused 19 more bombs, left at bus stops, theaters, pedestrian bridges and intersections. Investigators eventually tied the attack to a terrorist group based in Bangladesh.
Some intelligence experts faulted the government for failing to prevent the latest attack.
If you do not have any information, it is an intelligence failure," said Ajit Doval, a former director of India's Intelligence Bureau. "But if you have some information, and even then you cannot prevent the event, then it is the failure of the government."
But others said it was not so simple.
"These alerts are so routine that you cannot act upon these," J. N. Rai, a former official with India's Intelligence Bureau, said in a telephone interview.
Heather Timmons reported from New Delhi, and Gerry Mullany reported from Hong Kong. Malavika Vyawahare, Sruthi Gottipati and Hari Kumar contributed reporting from New Delhi, and Raksha Kumar from Hyderabad.
This article originally appeared in The New York Times.