El Salvador's government has stepped up its crackdown on gangs, or maras, as they are called.
Elite police units, armed and trained by US special police, have been attacking the two most violent gangs in Central America: the Mara Salvatrucha and the 18th Street.
Years into the crackdown, young men are familiar with the drill. They are deemd as suspects by having a gang's tattoos or simply for being young and male.
Alcides Enrique Grandos, an officer with the UTO (Operative Tactical Unit), said: "If they look more than 14 and 18-years old, we will stop them."
The police's way of cleaning up the streets is to lock gang members up, by the thousand.
But every night, police find at least eight bodies disposed of in bushes or left on San Salvador's streets.
Authorities say the gangs are fuelling the wave of violent crimes that has swept across the region.
|Police have sent thousands of |
gang members to prison
Officials say the hard-line approach is the way to combat gang violence. But years into it El Salvador is still one of the most violent countries in Latin America.
The streets are empty at night and people fear for their lives.
Elite units aim to strike at the heart of the gangs. Rapid response teams, backed by military patrols, target gang territory but the violence has not abated.
The government reported almost 4,000 murders in 2006.
Rodrigo Avila, the head of police, wants to hit the gangs harder.
He said: "We know we have to improve a lot but if you talk to the people, people really think that the law is not being enforced, that the law is not strong enough."
The government's hard-line approach has sent thousands of gang members to prison.
The cycle of violence is reminiscent of the 80's, when El Salvador was plunged into a 12 year civil war that killed at least 70,000 people.
The war indirectly gave birth to the gangs. Thousands of Salvadoran refugees fled to the US and there the gangs were founded.
Alex Sanchez arrived in the US when he was just seven.
|Alex Sanchez help start the Mara Salvatrucha|
in Los Angeles [Al Jazeera]
He says he felt isolated and vulnerable in a Los Angeles where gangs reigned and he did not feel that he belonged.
He became one of the founders of the Mara Salvatrucha.
Sanchez said: "When they killed one of the guys from one of the cliques ... it brought everybody into a whole different view of what they were involved in.
"It wasn't about the one on one fights, or the rumbles in the schools or in the parks. That was about a life, or taking somebody's life. And we had one taken."
Thousands of gang members were arrested in the US as part of Operation Community Shield, which was launched in 2005.
The US policy of deporting convicted gang members means that thousands have been sent back to El Salvador and a generation of Salvadoran gang members who grew up in the US are now on the streets of San Salvador.