About 60 inmates tied to the Zetas drug trafficking organization broke out of a Nuevo Laredo prison Friday, leaving seven members of a rival gang dead in their wake.

The late-morning escape is the latest violent episode in a prison that was the site of a massive breakout last year and where the Zetas execute with impunity those who displease them.

Five guards also are missing from the Centro de Ejecución de Sanciones No. 2, known by its acronym CEDES, where 151 inmates escaped in December.

After that escape, the prison's warden went missing. His replacement was stabbed to death in March during a confrontation in the prison.

Few details about the escape were released Friday. Officials from the state of Tamaulipas were not available for comment but did confirm the escape with a brief news release Friday afternoon. The state said 59 inmates escaped, but some Mexican news outlets put it as high as 66.

“The situation is currently under control and the facts are being investigated in a coordinated manner with local and federal authorities,” the news release read.

Webb County Sheriff Martin Cuellar said that like the December escape, Friday's was an effort by the Zetas to free members and potential recruits.

The gang is strapped for manpower as they face a crackdown by the federal government and a war against their former masters, the Gulf Cartel. The seven inmates killed were Gulf Cartel members, Cuellar said.

The Zetas have effectively run CEDES, executing rivals and disobedient members and orchestrating escapes when it pleases them.

Among the 151 escapees from December were men accused of having committed homicides inside the prison on behalf of the Zetas.

At the time, authorities said the escape was organized by the nephew of the Zetas' No. 2, Miguel Treviño Morales. There's not any evidence that those escapees came to the U.S. to avoid recapture, Cuellar said.

“We don't have any indication on that,” he said. “We had rumors back then, but we never could confirm any of it.”

As it did after the mass December escape, the administration of President Felipe Calderón seized on the prison break as an opportunity to criticize the Tamaulipas government.

Tamaulipas is a holdout of Mexico's former ruling party, the Institutional Revolutionary Party, which will challenge Calderón's National Action Party for control of the presidency next year.

A news release from the federal government said more than 400 inmates escaped from Tamaulipas prisons between January 2010 and March 2011, calling it “unacceptable” and saying the government “strongly condemns” the latest escape.

Similar prison breaks in the past three years have led to the firings of four prison wardens and two directors of Tamaulipas' state prison system.

The breakouts included 41 prisoners who escaped in Matamoros in March 2010, 85 others who busted out of Reynosa's state prison last September and another 17 prisoners who tunneled out of Reynosa's prison in late May.

Most of the escapees — including 35 of Friday's escapees — had been jailed on federal charges, usually meaning organized crime.

Tamaulipas is divided between the Gulf Cartel and Zetas gangs, onetime allies that have been warring bitterly for the past 18 months, leaving several thousand dead across northeastern Mexico.

Many of those jailed in the state are affiliated with one gang or the other.

Mexican soldiers several weeks ago took over many police functions in 22 Tamaulipas cities and towns — including Nuevo Laredo, Reynosa and Matamoros — while those forces are purged of officers thought to be colluding with the gangs and new recruits are trained.

Prison security has become a major challenge amid Mexico's crackdown on organized crime, which has crowded state jails nationwide with federal prisoners. Prison riots between gangs and jailbreaks, usually with the participation of wardens and guards, have become common. After the December prison break, 41 guards were charged with helping inmates flee.

Houston Chronicle Staff Writer Dudley Althaus contributed to this report from Mexico City.