Here is a chronology of attacks against major Indian cities or sensitive locations in recent years:
March: Blasts in a train station and a temple in Varanasi, leave 20 people dead, mostly devotees.
July: A series of seven high-powered blasts on suburban trains in India's business capital Mumbai kill 187 commuters and leave 800 injured. The attacks prompt India to freeze peace talks with Pakistan.
September: Thirty-eight people are killed and more than 100 injured in three nearly simultaneous blasts, including one in a mosque, in the town of Malegaon in Maharashtra state.
February: Attackers fire-bomb the Pakistan-bound Friendship Express passenger train, killing 66 passengers, mostly Pakistanis.
May: Eleven killed, 15 injured in blast at the 17th century Mecca mosque in the southern city of Hyderabad. Five more die when police fire at Muslim protesters.
August: At least 40 people killed and more than 50 injured as two bombs rock a crowded outdoor auditorium and a popular eatery in Hyderabad.
November: At least 13 people die in bombings outside court buildings in three cities in the northern state of Uttar Pradesh.
May: Eight blasts tear through the northern tourist city of Jaipur, killing 65 and injuring 150. A group calling itself the "Indian Mujahideen" claims responsibility.
July 26: Eight bombs go off in the high-tech southern city of Bangalore, leaving one dead and seven wounded.
July 27: A string of 16 or more bombs hit the communally tense western city of Ahmedabad in Gujarat state, killing 45 and injuring over 160. Indian Mujahideen sent a claim before the blasts.
September 13: A series of bomb blasts rock New Delhi, killing 22 and injuring 98 in busy upmarket shopping areas of the capital. Indian Mujahideen again claims responsibility.
October 30: A dozen bomb blasts rip through Guwahati, the main city of northeastern Assam state, killing at least 71 people and injuring more than 300.
November 26-29: Ten gunmen, armed with explosive devices, launch a coordinated attack on various high-profile targets in Mumbai, killing 166 people. India blames the attack on Pakistan-based militants and suspends peace talks with Islamabad.
February 13: A bomb rips through the popular German Bakery eatery in the western city of Pune, killing 16 people including several foreigners. The Indian Mujahideen is blamed.
July: Triple bomb blasts targeting diamond and jewellery trading districts in Mumbai leave 26 people dead. No group claims responsibility. No arrests have been made.
September 7: Bomb kills 13 people outside the High Court in New Delhi.