A maximum security alert has been sounded in Assam on Saturday after a string of overnight separatist attacks killed 19 Hindi-speaking people and wounded 25, officials said.
"Security forces have been put on high alert across the state after the attacks on innocent people by terrorists," Assam Chief Minister Tarun Gogoi said.
"Security offensives against the terrorists have been intensified," he added.
Police said suspected terrorists of the outlawed United Liberation Front of Asom (ULFA) attacked Hindi-speaking migrant workers in six separate locations in the eastern districts of Dibrugarh and Tinsukia late on Friday.
"The death toll could mount as we have reports of some more people injured in remote areas," said Tinsukia district magistrate Absar Hazarika.
Heavily armed ULFA rebels attacked two brick kilns, fired indiscriminately on shops and businesses owned by Hindi-speaking people, besides triggering an explosion near a tea garden.
"In all the incidents, the ULFA targeted Hindi-speaking people, most of them daily wage earners and petty traders," a senior police official said.
In 2000, ULFA terrorists killed at least 100 Hindi-speaking people in Assam in a series of well-planned attacks after the rebel group vowed to free the state of all "non-Assamese migrant workers".
"The immediate provocation for the attacks is the killing of five senior ULFA leaders by counter-insurgency forces in separate encounters in the past one week and the arrest of two of their frontline leaders in raids," said Hazarika.
The attacks have triggered fear and panic among hundreds of Hindi speakers, most of them working in brick kilns and doing odd jobs, in Assam.
"We fear more such attacks and are really worried for our lives. We have been residing in Assam for decades, but now we don't know whether to stay put or flee to safer areas," said Rajesh Tiwari, a coal trader in Tinsukia.
The ULFA is a rebel group fighting for an independent homeland since 1979.
"The attacks were reminiscent of the one we saw in 2000 and therefore there is a sense of panic," said Hariprasad Gupta, another trader in Tinsukia, originally hailing from the eastern state of Bihar.