| CIUDAD JUAREZ, Mexico
CIUDAD JUAREZ, Mexico Suspected drug hitmen burst into a party and killed 13 high school students, in Ciudad Juarez on Sunday, the latest massacre in one of the world's deadliest cities, the Mexican army said.
Gunmen jumped out of sport utility vehicles and fired at the students, who were celebrating victory in a local American football championship, in a house in the city across the border from El Paso, Texas, in the early hours of Sunday.
Pools of blood collected in the street outside the house.
"The men drove up in SUVs, they were well-armed. They went into the house and shot at everyone, you could hear the gunfire all around," a neighbour at the scene said.
Army spokesman Enrique Torres said the victims were between 15 and 20 years old, and an additional 17 party-goers were wounded in the shooting, some critically.
"They were about 15 men, they closed off the surrounding streets and began shooting at the house as they moved inside," Torres said.
It was not immediately clear why the gunmen attacked the students. But drug hitmen have attacked parties in the city, searching for rivals, while police have reported that some teenagers have been involved in kidnapping others.
Ciudad Juarez is the bloodiest city in Mexico's drug war as rival cartels fight over markets and control of smuggling routes into the United States.
Violence is escalating even as federal police and soldiers patrol the streets. Some 2,650 people were killed in drug violence in Ciudad Juarez last year and cartel murders have jumped since the start of 2010.
In some of the worst attacks, gunmen have stormed at least seven drug rehabilitation clinics in the manufacturing city over the past two years, targeting rival dealers. Two strikes in September killed 28 people.
Mexico is the key transit route for U.S.-bound cocaine from South America and a top producer of marijuana and heroin.
A military crackdown on rival cartels in Mexico has fuelled a surge in drug violence that has killed more than 17,000 people over the past three years.
(Additional reporting by Alejandro Bringas; editing by Mohammad Zargham)