Hundreds of Kenyan security forces in armored cars and helicopters pursued bandits Thursday in a lawless northern region where at least 75 people have died this week in a cycle of grisly killings.

Police said 26 children were among those shot and hacked to death in the violence in the Marsabit district of Kenya, just south of the Ethiopian border. Scores of people have been injured.

"The security operation will continue until peace is restored," the Kenyan police said in a statement. "We appeal to the affected people to remain calm and discard the temptation to avenge the attack as the security forces pursue the attackers."

There were also unconfirmed reports that five Kenyans from a local nongovernmental organization, Farm Africa, were missing and presumed to have been killed.

The fighting began when about 400 cattle rustlers killed about 50 ethnic Gabra villagers Tuesday in Turbi, a remote area of Kenya about 350 miles northeast of the capital, Nairobi, officials said. The Gabra villagers responded by attacking a truck full of rival Borana villagers, whom they accused of the initial massacre. Some security officials said the Borana raiders crossed over the border from Ethiopia.

Low-level violence in Kenya's arid east and north is frequent, as clans fight for scant resources. Livestock raids over the borders with Ethiopia and Somalia are common. But villagers called the violence this week the deadliest in recent memory. The situation remained tense, with thousands of terrified villagers flooding the roads to flee the region.

"When you have the environment degraded, it is always so that we are going to fight over the few resources that are left," said Wangari Maathai, a deputy environment minister who was awarded the Nobel Peace Prize in 2004.

Maathai said the remote northeastern region's environmental needs had long been neglected. "If they had resources, they would not be killing each other over grazing ground and water," she said.

The Kenyan Red Cross was sending emergency supplies and a medical team to attend the wounded.

A daily newspaper, the Standard, berated the government for historically neglecting the region and for failing to dispatch high-level officials after the massacre Tuesday.

The attackers "seem to have hived off one part of the country in which they continue to perpetrate anarchy as the government sits on its hands and treats insecurity in this border district with condemnable levity," the newspaper said.

Policemen surveyed bodies of victims Wednesday in northern Kenya's remote Marsabit region.