President Alvaro Colom declared a state of emergency in the northern Guatemalan province of Peten, which borders Mexico and Belize, in response to the killings over the weekend of 27 farmworkers by Mexico's Los Zetas drug cartel.

"We are willing to deal with these people," Colom told Mexico's MVS radio on Tuesday.

Sunday's massacre of 27 farmworkers, of whom 26 were beheaded, by Zetas gunmen was "totally barbaric," the president said.

"In the next 48 hours, there will be important arrests," providing investigators with more information about what happened at the Los Cocos ranch, Colom said.

Three eyewitnesses, including a wounded massacre survivor and a pregnant woman spared by the gunmen, have been placed in the witness protection program and are providing information to investigators, the president said.

About 30 to 40 heavily armed men arrived in Los Cocos looking for the ranch's owner, Otto Salguero, and attacked the farmworkers when they learned he was not there, police said.

Three of Salguero's relatives had been murdered on Friday and the ranch owner disappeared, officials said.

All the evidence points to the killings being linked to a "fight between drug traffickers," Colom said.

"Everything appears to indicate that it's about a dispute between two groups, and these poor people were laborers, no evidence of weapons was found, of absolutely anything," the president told MVS.

Police killed two suspected Los Zetas drug cartel members and arrested a third in a shootout near the ranch on Monday, Colom said.

The three men are suspected of belonging to the "Zeta 200" cell of Los Zetas, considered Mexico's most violent drug cartel, police said.

The gunfight with police and the arrest occurred in Santa Elena, a city near the Los Cocos ranch, a National Civilian Police, or PNC, spokesman said.

Colom, who visited the massacre site at the Los Cocos ranch, made the decision to declare the state of emergency during the Council of Ministers meeting Monday night, presidential spokesmen told Efe.

The state of emergency, which will be in effect for 30 days, took effect on Tuesday, allowing the security forces to operate with fewer restrictions as they hunt the killers.

Human rights activists, meanwhile, said they doubted that the state of emergency declaration would slow the wave of drug-related violence in Guatemala.

Members of the Human Rights Convergence umbrella group held a press conference Monday at which they condemned the massacre and called on Colom to take measures to fight organized crime.

"We need far-reaching measures, such as the strengthening of the state and a larger police presence, to directly fight those who operate with impunity," International Human Rights Research Center, or Ciidh, member Jorge Santos said.

A state of emergency declaration "is not an appropriate measure for dealing with extreme violence," Santos said.

"Guatemala is a paradise for committing crimes because the system does not provide guarantees for bringing the guilty to justice," Santos said, adding that the Central American country has only 25,000 police officers to protect its 14 million people.

The Los Cocos massacre is similar to those carried out by the army during the 1960-1996 civil war, Legal Action Center for Human Rights representative Mario Minera said.

Investigators have identified 15 of the 27 victims, of whom three were ages 17, 15 and 13.

Twenty-four of the victims were from Los Amates, a city in the Caribbean province of Izabal, and the other three were from Peten.

Los Cocos is located outside the city of La Libertad, about 630 kilometers (391 miles) north of Guatemala City.

Peten, a province covered by dense jungles, is used by international drug traffickers to smuggle narcotics from South America into Mexico.

Officials do not have detailed figures on the number of killings carried out by Los Zetas in Guatemala, but they say that the cartel has been behind at least a dozen massacres that claimed the lives of about 100 people since 2008.

Los Zetas has been blamed for several massacres in Mexico, including the killings last August of 72 migrants, the majority of them from Latin America, at a ranch outside San Fernando, a city in the northeastern state of Tamaulipas.

The cartel is also suspected of being behind the killings of 183 people whose remains were found in 40 mass graves in Tamaulipas in the past few weeks.

Heriberto Lazcano Lazcano, known as "El Lazca," deserted from the Mexican army in 1999 and formed Los Zetas with three other soldiers, all members of an elite special operations unit, becoming the armed wing of the Gulf drug cartel.

After about a decade on the payroll of the Gulf cartel, Los Zetas went into the drug business on their own account and now control several lucrative territories.

Los Zetas, in addition to trafficking drugs, is also involved in kidnappings, armed robberies and extortion rackets.