At least 16 small bombs exploded in the Indian city of Ahmedabad today, killing at least 29 people and wounding 88, a day after another set of blasts in the country's IT hub, officials said.
On Friday, eight bombs exploded in quick succession in the southern information technology city of Bangalore, killing at least one person and wounding six others.
Today's blasts were in Ahmedabad's crowded old city dominated by its Muslim community. One was in a metal tiffin box, used to carry food, another apparently left on a bicycle.
"The blasts occurred in 90 minutes, one in a hospital, others in the old city of Ahmedabad," Narendra Modi, the state's Hindu-nationalist chief minister told reporters.
There were two separate series of bombings, the first near busy market places. A second quick succession of bombs went off 20 to 25 minutes later around a hospital, where at least six people died, police said.
Several TV channels said they had received an email from a group called the "Indian Mujahideen" at the time of the blasts. The same group claimed responsibility for eight bombs that killed 63 people in the western city of Jaipur in May.
One television channel showed a bus with its side blown up, shattered windows and the roof half-destroyed. Another showed a dead dog lying beside a blown-up bicycle.
"The bus had just started when the blast happened," P. K Pathak, a retired insurance official who was travelling in nearby bus, said.
Another unexploded bomb was found today near a shopping mall in Bangalore, but it was unclear whether the bomb was newly planted or meant to have exploded during Friday's attacks, police said.
India's home ministry said on Friday it suspected "a small militant group" was behind the Bangalore attacks, while some police officials suspected the blasts could be the work of the banned Students Islamic Movement of India.
Some IT companies in Bangalore, known as India's Silicon Valley, were increasing security after bombs went off there. Each bomb had a similar explosive force to one or two grenades.
The city is a prominent software development centre and is also home to a major outsourcing industry.
Also nicknamed the "world's back office", Bangalore has more than 1,500 top firms, including Infosys, Wipro and the offices of global firms such as Microsoft and Intel.
In May, eight bombs killed 63 people in the western city of Jaipur.
Reuters