Indian police are investigating whether a shadowy Islamic militant group was responsible for a dual bomb attack that killed at least 16 people outside a movie theater and a bus station in the southern city of Hyderabad, a police official said on Friday.

The group, the Indian Mujahideen, is thought to have links with militants in neighboring Pakistan. India's recent execution of an Islamic militant is being examined as a possible motive for the bombings, said the official, an investigator who spoke on condition of anonymity because he was not authorized to reveal details of the probe.

Police have not detained anyone in connection with Thursday's attacks, the first major terror bombings in India since 2011.

According to a New Delhi police report, two suspected Indian Mujahideen militants who were arrested last year said during questioning that they had done reconnaissance of Dilsukh Nagar, the Hyderabad district where the blasts occurred. They had also visited various spots in New Delhi, Mumbai and Pune.

In a statement in India's Parliament, Home Minister Sushilkumar Shinde said that in response to the "cowardly terror attack", the government will "make all efforts to apprehend the perpetrators and masterminds behind the blast and ensure that they are punished as per the law".

Earlier on Friday, as he toured the site of the bombings, Shinde said there had been a general alert about the possibility of an attack somewhere in India for the past three days. "But there was no specific intelligence about a particular place," he said.

The bombs were attached to two bicycles about 150 meters apart in the Dilsukh Nagar district, Shinde said. He said in addition to the 16 dead, 117 others were injured.

The bombs exploded minutes apart in a crowded shopping area. The blasts shattered storefronts, scattered food and plates from roadside restaurants and left tangles of dead bodies. Passersby rushed the wounded to hospitals.

Top state police officer V. Dinesh Reddy said improvised explosive devices with nitrogen compounds were used in the blasts, which he blamed on a "terrorist network".

On Friday morning, police with cameras, gloves and plastic evidence bags used pointers to gingerly look through the debris. Officials from the National Investigation Agency and commandos of the National Security Guards arrived from New Delhi to help with the investigation.

"This (attack) is to disturb the peaceful living of all communities in Andhra Pradesh," said Kiran Kumar Reddy, the state's chief minister.