The seven men were believed to have been at a family party when they were gunned down Saturday night, said Arturo Sandoval, a spokesman for the attorney general's office in Chihuahua state, where Ciudad Juarez is located. Five were found dead in a car, and the other two were shot at the entrance of the home.
There have been several such massacres in Ciudad Juarez, a city held hostage by a nearly three-year turf battle between the Juarez and Sinaloa cartels.
Few residents now venture out to bars and restaurants. And like those attacked on Saturday, others have discovered that they aren't even safe in their own homes: Last month, gunmen stormed two neighboring houses andattending a party for a 15-year-old boy.
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Eleven other people were killed Saturday in the city, including two whose bodies were found dismembered, Sandoval said. On Sunday, two city police officers, a man and a woman, were shot to death inside their patrol car.
Ciudad Juarez, across the border from El Paso, Texas, has become one of the world's deadliest cities in the time that the two cartels have been fighting. More than 6,500 people have been killed since the start of 2008.
The U.S. Consulate in the northern city of Hermosillo, meanwhile, announced new travel restrictions for its U.S. employees in the states of Sinaloa and Sonora.
A consulate warden message said all official travel is banned along Benito Juarez highway between Estacion Don and Guamuchil, Sinaloa, "due to extreme threats of violence."
U.S. employees must travel in armored vehicles in the rest of Sinaloa, a state considered the cradle of the drug cartel by the same name and where drug-gang shootouts are frequent. The consulate made an exception for the city of Mazatlan, though it did not explain why.
In Sonora, the consulate said armored vehicles were required south of Ciudad Obregon and it banned travel south of Navojoa and in the mountainous areas in eastern Sonora.
U.S. personnel also must travel in armored vehicles in the area around Nogales, a town across the border from Nogales, Arizona, "due to widespread violence" and "the threat of known drug trafficking activity throughout northern Sonora."
U.S. employees traveling from Nogales, Arizona, to Hermosillo, can only use their own vehicles on the Mexican toll road Higway 15 during daylight hours, the statement added.
The U.S. State Department has increasingly taken drastic measures to protect U.S. employees in northern Mexico from rising violence, including temporarily closing some consulates.
In southern Mexico, meanwhile, police in Oaxaca city found a human head in a gift-wrapped box left Saturday night on the side of a cliff popular for its view of the picturesque colonial center.
Reporters at the scene saw a threatening message left with the head signed, "the last letter Z," an apparent reference to the Zetas drug gang.
The gruesome find came a week after two young men who had been involved in violent university protests and other conflicts were gunned down in the middle of the day in a public plaza.
An e-mail purportedly from the Zetas claimed responsibility for those slayings and said that the two were killed for falsely representing themselves as members of the gang.
Oaxaca state Attorney General Maria de la Luz Candelaria Chinas said the e-mail is suspected to be fake, although she said authorities had not ruled out the possibility that the Zetas sent it.
Mexican government officials describe the Zetas - former hit men for the Gulf cartel who became independent this year - as a sort of franchise with units across the country. But officials say some of those cells are copycats using the Zetas name to intimidate extortion and kidnap victims.
The Zetas have grown in power over the past decade, and experts warn their clout could grow following the death Friday night of one the gang's major enemies, Gulf cartel leader Antonio Ezequiel Cardenas Guillen. The kingpin, known as "Tony Tormenta" or "Tony the Storm," was killed in a shootout with marines.
Although there have been some beheadings in recent years, cartel-style violence is rare in Oaxaca, the capital of the southern state by the same name, especially compared to northern Mexico or the central Pacific coast.