07:34 BST
A bomb exploded at Chennai Central railway station at 7.15 am this morning, killing one woman, and injuring many others on board the train.
Blasts arose from two carriages of the Bangalore-Guwahati express train, which had arrived at platform 9 ten minutes earlier, witnesses have reported.
One man, who was on board the train, has been detained for questioning, said police.
The woman killed has been identified as 22 year old Swati from Guntur. It is believed a bomb was located under her seat.
The station has been cordoned off, as investigations take place. Police sources have said the bomb was detonated via mobile device with a "high probability" of a timer device, given the staggered blasts.
Security as other railway stations, airports, bus terminals, and other sites such as the Kalapakkam Atomic Power Plant has been increased in light of the bomb blast.
"I have ordered authorities to bring culprits to book. The injured will be get the best medical facilities. I appeal to the public not to panic and I wish to assure them that security agencies are taking adequate precautionary measures," Tamil Nadu Chief Minister, Jayalalithaa said in a statement shortly afterwards.
The incident comes amidst the country's staggered general election. Voting took place in Chennai last week.
See here for reports by Times of India, New Indian Express, Hindustan Times and The Hindu.