men wielding assault rifles attacked two bars in Torreon, killing eight people and wounding 15 others.

Gunmen working for organized crime groups staged attacks over the weekend on two bars in Torreon, a city in the northern state of Coahuila, and on a bar in Ciudad Juarez, a gritty border metropolis in Chihuahua state that has become Mexico’s murder capital, killing 13 people and wounding 18 others, officials said.

Initial reports said men wielding assault rifles attacked two bars in Torreon, killing eight people and wounding 15 others.

The gunmen arrived at the El 3-2 bar on Saturday afternoon in two SUVs and opened fire on patrons, killing four people, the Coahuila Attorney General’s Office said.

A fifth person died while being treated at a hospital, the AG’s office said.

Ten other people were hit by gunfire, with some of them reported to have serious wounds, the AG’s office said.

Gunmen attacked the Los Virreyes bar several hours later, officials said.

The masked gunmen opened fire with assault rifles on the bar’s patrons, killing two of them and wounding five others, the AG’s office said.

The gunmen killed another man while fleeing from the crime scene, prosecutors said.

Torreon was the scene in February and May of last year of attacks on bars that left 15 people dead and dozens of others wounded, with the majority of the victims being young people.

Prosecutors in neighboring Chihuahua state later reported an attack on bar in Ciudad Juarez.

Gunmen attacked the bar Sunday in Juarez, located across the border from El Paso, Texas, killing five men and wounding at least three others, the Chihuahua Attorney General’s Office said.

“When we got to the crime scene, we saw four victims inside the bar and another wounded, but he died while being transported to a clinic in a private vehicle,” AG’s office spokesman Julio Castañeda said.

One of the victims was a security guard who worked in the parking lot, initial reports said.

Ciudad Juarez has been plagued by drug-related violence for years.

The murder rate took off in the gritty border city of 1.5 million people in 2007, when 310 people were killed, then it more than tripled to 1,607 in 2008, according to Chihuahua state Attorney General’s Office figures, with the number of killings climbing to 2,754 in 2009.

More than 3,100 people were murdered in the border city last year, making 2010 the worst year since a war between rival drug gangs sent the homicide rate skyrocketing in 2008.

The killing has not slowed this year, with more than 350 people murdered in Juarez, the state AG’s office said.

The violence is blamed on a war for control of the border city being waged by the Juarez and Sinaloa cartels with backing from hitmen from local street gangs.