DES MOINES (AP) - A homeless man who's a registered sex offender was arrested after police said he grabbed a toddler and sexually assaulted her in the men's room of the downtown public library.

Police hailed library workers who pulled the girl away from the man as heroes.

James C. Effler Jr., 32, was charged with first-degree kidnapping, second-degree sexual assault and failure to comply with rules of the Iowa Sex Offender Registry, because he was not living at the address listed.

Police said Effler grabbed a 20-month-old girl as she played near a computer being used by her babysitter. Library employees helped the babysitter search for the child before hearing the girl cry from the restroom, which was locked, police said.

Employees called police and removed the door handle to reach the girl, then held Effler until officers arrived, Capt. Kelly Willis said.

"Most of the police work was done by the library staff before we even arrived," Willis said.

The child was taken to a hospital for evaluation. The extent of her injuries was not made public.

Effler was convicted in 2003 for a sex crime against a 31-year-old woman in El Paso, Texas. He was sentenced to three years in prison and later paroled.

Police have not determined how long Effler has been living in Iowa.

Effler is listed on the state registry, but because his conviction involved an adult victim, he is not covered by the state law that prohibits some offenders from living within 2,000 feet of a school or child care center.

Police said Effler was living at a homeless shelter.

When library workers heard the girl scream in the restroom, they saw an adult's shadow on the other side of the door's frosted glass, police said.

When they couldn't force their way into the restroom, they called for a maintenance worker with a screwdriver, Willis said. Once the door handled was removed, they opened the door, pulled the child out and shut Effler inside.

"They are heroes," Willis said. "They grabbed the baby and shut the door on him."

Records show that in recent months, Effler was jailed for public urination, arrested for drunken driving and charged with shoplifting.