The attacks took place in the two districts of Kokrajhar and Sonitpur, senior state police official SN Singh said, with the deadliest claiming 26 lives.
Police blamed the attacks on the outlawed National Democratic Front of Bodoland (NDFB), which has been demanding a separate homeland for decades.
“Of the 34 killed in the two districts, 26 were in Sonitpur district, “Singh told AFP.
“There has been about four separate attacks by the NDFB,” he said.
The authorities have issued a ‘red alert’ in the state and imposed a night-time curfew, NDTV news channel reported.
Singh added that most of the victims of the latest fighting in the area, a site of frequent ethnic clashes, were members of the Adivasi tribal community, primarily tea plantation workers.
Assam, a tea-growing state that borders Bhutan and Bangladesh, has a long history of often violent land disputes between the indigenous Bodo tribes, Muslim settlers and the Adivasi community.
About 10,000 people fled their homes in northeast India when violent clashes over a border dispute left more than 45 people dead earlier this year. In 2012, ethnic clashes in the same area in Assam claimed about 100 lives and displaced more than 400,000 people.