Another 17 people were injured in a stampede that followed the blast in Imphal, the capital of Manipur state, while Hindus were celebrating the birthday of the Hindu god Krishna, Col. S. D. Goswami, the spokesman, said. The temple belongs to the International Society of Krishna Consciousness.
The attack occurred despite tight police and paramilitary security in and around the temple where hundreds of Hindus congregated for the festival.
No one claimed responsibility for the blast and the attackers escaped.
Dozens of insurgencies have festered for years across India's seven northeastern states, of which Manipur is one. Nearly all are fighting for autonomy or independent homelands for the region's indigenous peoples, most of them ethnically closer to Burma and China than to the rest of India.
The militants say the central government in New Delhi — 1,000 miles to the west — exploits the northeast's rich natural resources while doing little to improve its poor infrastructure and alleviate widespread unemployment.