Gunmen opened fire on four women and a child in Chihuahua city, the capital of the like-named northern Mexican state, killing two of the women and wounding the others in the group, police said.

The gunmen drove up to a clinic on Monday in a small car, got out of the vehicle, opened fire on the group and then fled.

The two wounded women and the child were taken to a hospital, where they are listed in serious condition.

Chihuahua is considered Mexico's most violent state, topping the homicide list since 2008.

The state is home to Ciudad Juarez, a border city located across the Rio Grande from El Paso, Texas, where more than 3,100 people died in drug-related violence last year.

The killing has not slowed this year, with more than 1,100 people murdered in Juarez.

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.

At least 14,000 "armed criminals" are in Ciudad Juarez and Chihuahua city, working for the drug cartels that are fighting for control of smuggling routes into the United States, Chihuahua Attorney General Carlos Manuel Salas said last month.

"It was an inherited war, which we got from the prior administration, in which 9,000 armed criminals are fighting for Juarez and a number near 5,000 for the city of Chihuahua," Salas said.

About 5,500 of the armed criminals operating in Ciudad Juarez belong to Los Aztecas, a gang that works as the armed wing of the Juarez cartel, while the rest work for the Sinaloa cartel, Salas said.

About 40,000 people have died in drug-related violence since President Felipe Calderon declared war on Mexico's cartels shortly after taking office in December 2006.