Violent drug wars have turned the streets of Ciudad Juarez into danger zones for police and civilians alike [Reuters]

At least 13 young people have been shot dead and 15 wounded in an attack on a house party in the Mexican city of Ciudad Juarez, the second such massacre in less than a week in the violent border city.

Prosecutors said on Saturday that the victims were aged 14 to 20 years, and that a nine-year-old was among the wounded.

"A group of heavily armed men arrived in two minivans. At least 10 men burst into the party," Carlos Gonzalez, a spokesman for state prosecutors, told the Reforma newspaper.

The partygoers had gathered for a 15-year-old boy's birthday party on Friday.

"The victims were in the back yard of the house having a party when hooded men, in dark uniforms and with rifles, arrived in several vans, broke in and began shooting indiscriminately at those inside," a police official said.

The attackers escaped, and police said they had no immediate information on any suspects or possible motive.

Seventy bullet casings from assault weapons typically used by drug gangs were found at the scene.

Local media, which showed images of bodies strewn among cars parked in the garage of the house, said 15 people were killed and 18 wounded, but that toll could not be independently verified.

The massacre occurred in a residential district known as Horizontes del Sur, which has experienced a shocking rate of violence.

On Wednesday, a couple was shot and killed while driving through the neighbourhood. The Latin American Herald Tribune newspaper reported that the couple's two-year-old child was found alive in the vehicle, "splattered with his parents' blood".

On Sunday, armed men stormed two homes in another part of Ciudad Juarez. Seven people were killed at a party and two more in another house nearby.

Investigators later said the attack was apparently carried out by Juarez cartel gunmen looking to kill allies of the Sinaloa cartel. There was no evidence the youths were the targets, and police said the killers may have hit the wrong house.

More than 2,000 people have been killed in drug-related violence in Ciudad Juarez in 2010, and the city is considered the country's murder capital..

Source: Agencies