SAN DIEGO -- In an effort to stop truancy among middle school and high school students, the San Diego Police Department and Child and Protective Services joined forces to slow the growing trend of skipping school.

However, during the "truancy sweep," police made a disturbing discovery. They found out that children were being recruited into gangs to be used as prostitutes.

The girls, some only in middle school, were being targeted by predators who want to recruit them into prostitution.

Officer Thomas Williams has been patrolling El Cajon Boulevard for almost 20 years. In recent times, he has noticed more young girls selling themselves on the streets.

"I've seen some as young as 14 and 15 on the boulevard," Williams said.

The people who deal with the child prostitution issue on a daily basis said one group is responsible for recruiting more than half of the underage prostitutes. It is a group known as "Pimp 'n Hoes Daily" or PHD. They said some of their young recruits aren't even in high school yet.

"I've met girls as young as 10," Williams said.

"I can drive down El Cajon Boulevard and tell you which ones are working, even though 80 percent of them are under 18," said Kathi Hardy, from Freedom From Exploitation, a teen prostitute task force.

Officers picked up 44 children in a truancy sweep in the City Heights area.

Most were simply skipping school, but police worry the children will be tempted into a life of crime and that girls will be targeted by groups like PHD, which uses threats and promises of riches to coerce underage girls into prostitution.

San Diego police Sgt. Juan Gonzales said, "Our detective unit currently has an investigation working on that group."

Gonzales said San Diego police detectives are also working with Tijuana police. Many of the girls recruited by PHD and other gangs are being taken across the border and sold on the streets in Mexico.

"We need to bust up this organization that does nothing but prey on innocence," said Hardy.

Last year, San Diego police contacted 184 underage girls who were suspected of being involved in prostitution. The numbers for this year are not out yet, but officers say the problem seems to be getting worse, not better.