HOUSTON (AP) - Texas authorities are trying to figure out how a 16-year-old may have gotten a loaded handgun past officers at a juvenile detention center in Houston.

Guards at the Harris County Juvenile Detention Center discovered the gun about two hours after the youth was booked for marijuana possession Monday morning.

Juvenile Probation Department director Harvey Hetzel says the .25 caliber semiautomatic handgun was found under the teenager's mattress.

Houston police spokeswoman Jodi Silva said her agency is investigating how the teen concealed the gun through three searches, including one during his arrest.

Hetzel says juveniles are generally searched, photographed and fingerprinted at a processing center then strip-searched at the downtown detention center.

Information from: Houston Chronicle, http://www.houstonchronicle.com