The incident started around 3:35 p.m. Thursday at a home on the 900 block of North Humboldt Avenue.
After a five-hour standoff, police found 34-year-old Luis Rios hiding in the attic of the home with the victim. He was believed to be armed with a handgun.
Officers arrested Rios after he fell through the ceiling. The hostage was expected to be OK. More than 20 homes had to be evacuated during the standoff.
Rios was wanted by Pomona police for assault with a deadly weapon and sexual assault of a minor. The hostage was the same victim identified in the Pomona sexual assault investigation, officials said.