The death toll from this week's bombings in India's financial capital rose to 19 as Mumbai police continued Saturday to systematically sift through the evidence gathered from the site of the three blasts.
A police official said teams of investigators had fanned out to at least three different cities in the country to probe the existence of groups that may have links to the bombings.
The death toll in the blasts climbed to 19 when two injured men succumbed to their wounds, another police official said Saturday.
Both officials spoke on condition of anonymity because they were not authorized to speak to the media.
More than 100 people were still in hospitals in Mumbai being treated for wounds sustained when the bombs went off Wednesday evening.
No group has claimed responsibility for the bombings, and investigators have not named any suspects.
The teams of investigators were questioning suspected members of militant organizations in the southern cities of Bangalore and Hyderabad and the eastern cities of Ranchi and Kolkata, one of the police officials said.
Investigators say the attack bore the hallmarks of the Indian Mujahideen, an Islamic militant group linked to Pakistan's Lashkar-e-Taiba that has claimed past attacks that used similar explosives.
The blasts were the deadliest attack in Mumbai since a 2008 siege in which 166 people were killed in an assault that lasted three days.
Intelligence agencies were also examining Mumbai's criminal underworld, said Prithviraj Chavan, the top elected official in Maharashtra, the state of which Mumbai is the capital.
"All angles are being probed. We have set up many investigating teams, including one to probe if the underworld had a hand in the blasts," Chavan said Saturday.
Mumbai's criminal gangs are headed by India's most wanted man, Dawood Ibrahim, the alleged mastermind behind bombings in Mumbai in 1993 that killed 257 people.
Ibrahim fled Mumbai and police now believe he lives in Karachi in Pakistan.
Pakistani officials deny that Ibrahim is in Karachi.