A bomb exploded in a busy market in India's restive northeast, killing eight people and injuring 19, and authorities said they discovered and defused an explosive device hidden on a crowded passenger train headed for the area. There was no immediate claim of responsibility in either incident Saturday, 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 over the past two months, police said. In Saturday's 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, police found an unclaimed steel box Saturday on a train traveling from New Delhi to Gauhati during a routine check at a station stop 200 kilometers (125 miles) outside of Gauhati, said railway official T. Rabha. Inside the box, police found a 10-kilogram (22-pound) bomb, which the army later defused, said Rabha. Officials believe the incidents might be pegged to the state government's one-year anniversary of holding power, which was to be marked Sunday with public events. The state government is ruled by the Congress party, which also leads the governing coalition in New Delhi. 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. "We are bent on going ahead with our celebrations tomorrow." 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 1,600 kilometers (1,000 miles) to the west. They also accused the government of exploiting the northeast's rich natural resources.