Nearly simultaneous explosions from homemade bombs planted outside courts in three northern Indian cities killed at least 13 people in what a senior government official said were terrorist strikes.
Officials said 59 people were wounded in the blasts at Varanasi, Faizabad and Lucknow, all in the populous state of Uttar Pradesh. Many of the dead were lawyers.
At least nine people were killed in Varanasi, one of India's most sacred Hindu pilgrim centers, Uttar Pradesh Chief Minister Mayawati, who uses only one name, told reporters.
Four people were killed in Faizabad while there were no casualties in the state capital Lucknow.
All three cities have a history of communal tensions between India's majority Hindus and its minority Muslims.
I believe it is the handiwork of groups who are trying to spread terror in our country, junior Home Minister Sriprakash Jaiswal told reporters.
India has been hit by blasts frequently in recent years and most of them have been blamed on Pakistan-based Islamist militant groups fighting against Indian rule in Kashmir.
Local TV channels showed what appeared to be at least one dead lawyer, dressed in traditional black clothes, lying on the ground. Dry leaves had fallen over his body.
Another body was lying face down in a pool of blood.
One injured man rode away on a motorcycle while a passerby held a cloth or handkerchief to his blood-soaked head.
At least 15 people were killed and 60 wounded in three explosions in Varanasi in 2006.
Faizabad is a twin city of Ayodhya, a Hindu holy centre where hardline Hindu groups razed an ancient mosque in 1992, saying it was built on the birthplace of Hindu god-king Ram.
Ayodhya has since been a flashpoint for Hindu-Muslim tensions across the country and the disputed site was also targeted by suspected Muslim militants in 2005.
Outside the Lucknow court, where police said the explosive was attached to a motorcycle, lawyers gathered after the blast to shout Down with Pakistan.
The lawyers said they suspected the blast was in retaliation for an attack by a mob on three suspected militants of a Pakistani-based group when they appeared in court a few days ago.
Police said the suspects had plotted to kidnap a top Indian politician.
Last month, a small bomb exploded just after evening prayers at Ajmer, an important and crowded Muslim shrine in northwestern India, killing at least two people.
Indian officials say that militant groups target religious centers in an attempt to divide majority Hindus and minority Muslims and spark clashes.