Despite the violence, President Felipe Calderon hotly disputed a statement this week by U.S. Secretary of State Hillary Rodham Clinton that Mexico resembled Colombia two decades ago, when the South American country was in the grip of a drug-financed insurgency.

"These kind of comments like the ones made by Secretary of State Clinton … damage Mexico's image terribly," Calderon told the Spanish-language network Univision. "I think the main thing we have in common with Colombia is that both of our countries suffer from U.S. drug consumption."

The toll in Thursday's killings included 15 people slain when attackers stormed four homes in three hours, said Arturo Sandoval, a spokesman for the attorney general's office of Chihuahua state, where Ciudad Juarez is located.

Sandoval said it was the highest single-day homicide toll since March 2008 for the city, which lies across the border from El Paso.

In Reynosa, across the border from McAllen, Texas, 85 inmates — 66 of them convicted of or on trial for federal charges, including weapons or drug possession — scaled a prison's 20-foot walls using ladders, said Jose Garza Garcia, Tamaulipas state public safety secretary.

Garza Garcia said 44 prison guards and employees were under investigation. Two were missing. "The guards evidently helped in the escape," he said.

So far this year, 201 inmates have escaped in Tamaulipas.

Ciudad Juarez, with a population of 1.3 million, has become one of the world's most dangerous cities amid a turf war between the Sinaloa and Juarez drug cartels.

More than 2,100 people have been killed this year in the city, putting it on pace to surpass its previous high of 2,700, set last year.

Daily homicide tolls routinely reach double digits in Juarez. On Aug. 15, 24 people were killed.