NEW DELHI -- Two bombs on Thursday killed at least 13 people and wounded some 70 in a busy shopping district in the southern city of Hyderabad at the height of the evening rush hour, the largest terrorist bombing in India since September 2011.
Sushil Kumar Shinde, India's home affairs minister, said the central government had warned state governments that such an attack was planned. "We have had some information for the last two days of such an incident," he said.
Hyderabad, one of India's largest cities and a leading center of the country's growing pharmaceutical and biotechnology industries, has suffered other such attacks in recent years, usually linked to sectarian friction.
The blast sites on Thursday -- in the Dilsukhnagar neighborhood, packed with shops, restaurants, theaters and a huge produce market -- were quickly mobbed by protesters, reporters, curious onlookers, and politicians and their entourages. Television news footage in the hours afterward showed chaotic scenes, with some investigators trying to find the remains of the explosive devices, which were planted on bicycles, while huge numbers of people jostled for space around them.
Mr. Shinde, speaking to journalists in New Delhi, said that the bicycles were 150 meters away from each other and the bombs detonated about 10 minutes apart, killing eight at one site and three at the other. But he forewarned that the toll could rise, and it did so, with 13 reported dead by midnight.
In a Twitter message, Prime Minister Manmohan Singh said, "This is a dastardly attack, the guilty will not go unpunished."
They and other officials sought to diminish the chances of the kind of sectarian rioting that has long plagued the country.
Asked in a news conference if he believed that Muslim extremists were to blame for Thursday's blasts, Mr. Shinde said, "We have to investigate. We should not come to conclusion immediately."
In another Twitter message, Mr. Singh said: "I appeal to the public to remain calm and maintain peace."
Asaduddin Owaisi, a Muslim member of Parliament from Hyderabad, called the blasts "cowardly."
"I feel that the priority is to maintain peace," he said. "Let us not fall prey to rumors."
The crush of government officials at the blast sites, along with their large entourages and their own police squads, was portrayed by the news channel NDTV as particularly unhelpful. The money and resources spent on protecting government officials and politicians has become a source of increasing controversy in India, especially when security for ordinary people is lacking, as was underscored recently by a highly publicized gang rape case in December in New Delhi. Indian politicians, like those elsewhere, often compete with each other to show who is tougher on acts of terrorism and other crimes.
"We've seen political leaders come into the area and hold press conferences," an NDTV anchor said. "That's the last thing they should be doing."
Nallari Kiran Kumar Reddy, the chief minister of the state of Andhra Pradesh, held a news conference away from the scene late Thursday night and asked people to stay away from the blast areas. Renuka Chowdhury, a leader of the Indian National Congress Party, pleaded with other politicians to stay away as well.
"I really wish politicians would recognize this," Ms. Chowdhury said.
The bombings in recent years in Hyderabad have often used homemade explosives.
In May 2007, 13 people died after a bomb went off at the Mecca Masjid, a mosque there, including some who were killed in clashes between the police and Muslim protesters afterward. In August 2007, a pair of synchronized explosions tore through two popular gathering spots in Hyderabad, killing at least 42 and wounding dozens. In the hours after the blast, police found and defused 19 more bombs, left at bus stops, theaters, pedestrian bridges and intersections.
In New Delhi in September 2011, a briefcase exploded near the high court, killing at least 12 people and injuring scores.
Hari Kumar contributed reporting.
This article originally appeared in The New York Times.