The agency said the first bomb went off near the police station in Jorhat, 310 km (190 miles) from the state's largest city of Guwahati, killing two and wounding 10.
"The bomb was planted in a bicycle near the police station," Johart's police chief said.
Another home-made explosive hidden in a garbage can injured two people in Guwahati.
This is the second wave of militant attacks to hit the region in the past few days. A total of 33 people were wounded in two explosions in Assam on Sunday. Local authorities said the surge in terrorist activity was linked to the approach of the 60th anniversary of India's independence, on August 15.
Chief Minister of Assam Tarun Gogoi blamed the locally-based United Liberation Front of Asom for the attacks. Outlawed in 1979, the militant group has been fighting for "a sovereign socialist" state in Assam, world-famous for Assam tea and silk.
There are up to 30 armed groups active in northeast India, each pursuing their own goals of independence or greater autonomy.