The director, who was tied up with power cords Tuesday, eventually broke free and called police, American Fork police Sgt. Shaun Greening said. She also freed another pregnant teen tied up in the attack, he said.
Authorities believed the teens — two 15-year-olds and one 16-year-old — left the state and a search was under way. Police said the teens also stole the director's purse, checkbook, credit cards, cell phone and video camera.
The motive wasn't clear. Parents of the girls, who are from California, Texas and Illinois, were notified, police said.
The home, a place for struggling pregnant teens, is in Utah County, about 30 miles south of Salt Lake City. Pregnant teens are typically sent there by parents to get away from problems with drugs or boyfriends. They attend class and learn about prenatal care, childbirth and adoption while staying at the home, according to police.