Up to 150 people have been shot dead or drowned in a river in northeastern Nigeria while fleeing violence by the Boko Haram Takfiri terrorists.

Witnesses and local residents said on Tuesday that Boko Haram militants on motorcycles and in a car attacked the remote village of Kukuwa-Gari in the violence-hit Yobe State on August 13.

"They opened fire instantly, which forced residents to flee. They shot a number of people. Unfortunately many residents who tried to flee plunged into the river, which is full from the rain. Many drowned," AFP quoted Modu Balumi, a resident of the village, as saying. "By our latest toll we have 150 people either (shot dead) or drowned in the attack. The gunmen deliberately killed a fisherman who tried to save drowning residents of the village."

Witnesses said the bodies of many of the drowned were pulled out by locals several kilometers away.

The news of the ambush took five days to emerge because the terrorists have destroyed telecommunications masts around the village.

The Gujba area of Yobe, where Kukuwa-Gari village is located, has been hit hard by militancy and violence in the past.

Nigerian President Muhammadu Buhari, who came to power in late May, replaced the heads of the army, navy, air force and his chief of defense staff in an effort to re-energize the fight against Boko Haram.

The terrorist group has stepped up its attacks since Buhari, a former army general, came to power on May 29. President Buhari has vowed to curb Boko Haram’s militancy.

According to a count by the AFP, a wave of raids, bombings and attacks has left at least 1,000 people dead in Nigeria alone in less than three months.

The Boko Haram militancy began in 2009, when the terrorist group started an armed rebellion against the government of Nigeria. Amnesty International says 17,000 people have been killed since then.

Boko Haram violence has spilled over into Nigeria’s neighboring countries. Soldiers from Nigeria, Chad, Cameroon and Niger have been battling the terrorists in recent months.

Nigeria's neighbors, which have all suffered attacks by Boko Haram, set up a regional force earlier this year to end the conflict.