GAUHATI, India – Clashes between ethnic groups in India's remote northeast has left at least 49 people dead in four days including 19 killed on Monday, officials said.

The fighting in Assam state began Friday when a group of young ethnic Bodo men were attacked after patrolling their villages. Bodo leaders blamed relatively recent settlers, most of whom are Muslims, for sparking the clashes, said Assam Home Commissioner Subhash Das.

But authorities said the National Democratic Front of Bodoland, a Bodo separatist group with a history of violence, were targeting Muslim settlers.

Ethnic Bodos and Muslim settlers in Assam have a history of conflict and have fought recently with bows and arrows, spears and machetes, and have burned each other's homes and property, officials said over the weekend.

More than 150 people have been injured in the violence and more than 100,000 have fled their homes in some 30 villages, Das said.

“This is a clear case of ethnic cleansing by the NDFB,” said Assam government spokesman Himanta Biswa Sarma. He said Bodo militants were coordinating attacks with violent mobs who were burning Muslims' homes.

In an e-mail sent to journalists Sunday night, the Bodo group's spokesman, S. Sanjarang, denied any role in the fighting.

The 49 people killed since Friday include 15 people who were fatally shot when police opened fire on violent mobs in at least four different incidents, said Sarma. Police have been authorized to shoot at anyone fighting in the streets.

An indefinite curfew imposed Friday in the northern Assam districts of Udalguri and Darrang continued Monday with small breaks to allow people to buy essential supplies.

Animosity between the Bodos and Muslim migrants stems from long-standing land disputes. The groups clashed sporadically throughout the 1990s, leaving at least 250 dead and an estimated 300,000 displaced.

Nearly 100,000 people are still living in makeshift relief camps.