The explosives, hidden in plastic bagsin the main court of the Jama Masjid mosque in Old Delhi, went off just after evening prayers had finished.
Earlier in the day, at least five people were killed in a series of grenade attacks in Srinagar, the summer capital of Indian-held Kashmir. It was not clear if the two attacks, which came as much of India celebrated Hindu New Year, were linked.
Just a short while before the Jama Masjid bombs exploded, the mosque was crowded with 15,000 Friday worshippers. Most had left by the time the bombs went off; had they detonated sooner, there could have been many casualties.
The Jama Masjid, built in the 17th century by Mughal emperor Shah Jahan, is one of Delhi's main tourist sites and one of India's most revered mosques. The vast building was not damaged. and there was no indication who was behind the attacks.
That it targeted a Muslim holy site suggested the attacks could be meant as a retaliation for bombs which killed 15 people in the Hindu holy city of Varanasi last month.
In Kashmir, the violence began when a grenade was thrown at an Indian military truck in central Srinagar. Minutes later two passers by were killed in a second grenade attack. By the end of the day there were five such attacks. All of the dead were civilians.
It was the most serious violence in Kashmir for some months. Four Islamist militant factions fighting against Indian rule in Kashmir claimed responsibility.Reuse content