CIUDAD JUAREZ, Mexico -- Gunmen killed 25 people in a series of drug-gang attacks in Ciudad Juarez, marking the deadliest day in more than two years for the Mexican border city, authorities said Friday.
Thursday's toll included 15 people killed 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.
In the worst of those attacks, gunmen burst into a house and killed two young men -- then killed four others for being witnesses.
Sandoval said it was the highest single-day murder toll in the city across from El Paso, Texas, since March 2008. He did not give more details of how many died back then, or say what day.
Two graffiti message appeared in Ciudad Juarez threatening Joaquin "El Chapo" Guzman, the fugitive head of the Sinaloa drug cartel.
"You are killing our sons. You already did, and now we are going to kill your families," one sign read.
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 cartels.
Violence has continued unabated despite the deployment of thousands of soldiers to the city this year. Federal police, including a special investigative unit, later took over security in the city as part of a new strategy announced by President Felipe Calderon.
More than 2,100 people have been killed this year in Ciudad Juarez, putting the city on pace to surpass its previous high of 2,700, set last year.
Daily homicide tolls routinely reach double digits in Juarez; 24 people were killed Aug. 15.
Also Friday, Sandoval confirmed that a U.S. resident kidnapped in Ciudad Juarez last month was found dead.
Saul de la Rosa, 27, was abducted along with two other people when he crossed into Ciudad Juarez on Aug. 28. All three bodies were found Sept. 2, and Sandoval said documents found on De la Rosa indicated he was a U.S. resident.
Elsewhere in Mexico, at least five people were killed in the southern Pacific coast state of Guerrero, where various cartels are also fighting for territory, state police reported. One body was found floating in the ocean in a beach town just north of the resort city of Acapulco, his hands and feet bound.