A bomb exploded in a busy market in India's restive northeast Saturday, killing eight people and injuring 19, and authorities said they discovered and defused a large bomb hidden on a crowded passenger train headed for the area.

There was no immediate claim of responsibility, but police were investigating whether the United Liberation Front of Asom, a separatist rebel group, was involved. The ULFA, which has been fighting since 1979 for an independent homeland in Assam, has set off more than 20 bombs in two months, police said.

In the market blast, the explosives were packed in a three-wheeled auto-rickshaw, said S.N. Singh, police chief of Gauhati, the capital of the state of Assam.

Separately, officials defused a 22-pound bomb inside an unclaimed steel box that was found on a train during a routine check at a station stop 125 miles outside of Gauhati, said railway official T. Rabha.

The state government's one-year anniversary of holding power was to be marked Sunday with public events. A state minister, Himanta Biswa Sharma, said the festivities would go on as planned.

"We are not going to be cowed down by today's explosion," said Sharma.

Federal authorities have sent extra troops to the region.

Peace talks between the ULFA and the Indian government broke down in September last year after a six-week truce. ULFA responded with violence, killing more than 70 Hindi-speaking migrant workers across Assam.

The rebels say Assam's indigenous people, most of whom are ethnically closer to Myanmar and China than to the rest of India, are ignored by the federal government in New Delhi, some 1,000 miles to the west. They also accused the government of exploiting the northeast's rich natural resources.