The number of injured from the Saturday night attacks also has gone up from 88 to at least 162, they added.

All metropolitan areas in India were on high alert, a day after 17 blasts of low intensity went off within a span of 70 minutes and a 6-mile (10-km) radius in eastern Ahmedabad.

One explosion hit a bus stop, while others detonated at a railway station and on a bus. Several also went off at or near hospitals where the injured were being taken.

Authorities raided an apartment rented by two "foreign nationals" in Mumbai, 338 miles (545 km) away after tracing an e-mail that claimed responsibility for the blasts.

No arrest has been made, although police reportedly rounded up 30 individuals in connection with the blasts.

The serial blasts also occurred barely 24 hours after nine similar blasts rocked Bangalore, known as the Silicon Valley of India. Two people were killed and six injured in those explosions.

In both cities, bicycles, bags and lunch boxes were repositories for the bombs, authorities said.

Ahmedabad, the largest city in Gujarat state, was the scene of deadly Hindu-Muslim riots in 2002 that left about 1,000 people dead.