Indian cities have been put on high alert after the second wave of serial bomb blasts to strike the country in two days killed at least 45 people and injured more than 161 in the western city of Ahmedabad.

The series of at least 16 small bombs, which mostly struck the old city of Ahmedabad, capital of India’s mercantile Gujarat state, on Saturday, came only a day after a similar wave of blasts left one person dead in Bangalore, India’s Silicon Valley.