San Mateo city police have arrested a 19-year-old Los Altos Hills man who parents reported was loitering outside a youth gymnastics center and taking photos of children with his cell phone.

Edward George Mielke had been "hanging around" Peninsula Gymnastics, in the 1700 block of Leslie Street in San Mateo for the past several weeks, police said. When officers contacted Mielke, they examined his cell phone and found numerous pictures of children taken outside the business.

They also found other photos of children taken at unknown locations and pornographic images of children downloaded from a foreign web site.

In 2011, the California Supreme Court ruled police do not need a warrant to search cell phones of people they arrest. Sgt. Dave Norris, a spokesman for the San Mateo police, said he would not comment on the specifics of how police accessed Mielke's phone.

Police said that Mielke apparently did not enter the gymnastics center. Upon a search of the house where Mielke lives, police found what they described as "additional suspicious photographs and materials."

Mielke was booked into San Mateo County Jail on charges of possessing child pornography, and child annoyance.

Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN