GUWAHATI, India, Jan 23 (Reuters) - Two bombs and a grenade attack in India's troubled northeast on Tuesday killed a man waiting at a bus stop and injured many others, a senior police official said, blaming the attacks on separatist rebels. The first bomb was hidden in a bag and detonated near a crowded bus stop in Guwahati, the main city in Assam state. Minutes later, another a bomb exploded in a crowded market in the west Assam town of Bongaigaon -- the second of the day -- injuring seven people, one critically. No one was injured in the earlier attack at the same market. Separately, a grenade was lobbed into a crowd in the small town of Kamalpur, wounding four people including a 16-year-old girl. Police blamed the attacks on the United Liberation Front of Asom (ULFA), which has been fighting for Assam's independence and has stepped up violence since peace talks with New Delhi failed last year.