Police have accused a 15-year-old Westchester boy in two knifepoint abductions and rapes, including one where an 11-year-old girl who was walking home from a Christmas concert at a local library last December.

The 15-year-old boy from Mount Vernon was arraigned Wednesday on a 28-count indictment that included charges of rape, kidnapping, sexual abuse and child endangerment, the Westchester County District Attorney said. 

The teen allegedly abducted a 23-year-old woman walking home from work in Mount Vernon on Oct. 20 and forced her to the nearby Grimes Elementary School while holding a knife to her throat, prosecutors said. 

He forced her to perform sex acts on him and raped her several times, prosecutors said. After the attack, he walked with the victim to the corner and let her leave and she immediately notified police.

The teen also allegedly abducted an 11-year-old girl while she was walking home from a Christmas concert at a local library in Mount Vernon at about 8 p.m. on Dec. 4. He took her to Grimes Elementary School, where he forced her into sex acts and raped her multiple times during a two-hour attack, prosecutors said. 

When the child screamed at one point, the teen, who was holding a knife, allegedly threatened to kill her, according to prosecutors. The girl was eventually let go.

Police had no leads in the investigation until they interviewed the teen in an unrelated case, prosecutors said. They collected DNA the teen left on a water bottle he drank from, and forensics teams matched the one found in the two rapes.

The teenage suspect, identified as Javon Roberts, is being charged as an adult, but the district attorney's office said that because of his age, he's considered a juvenile offender under state law. The maximum sentence he can receive if convicted is 10 years. 

Roberts has been remanded to jail until his next court appearance on May 12.

No one answered the door at Roberts' listed home address Thursday. 

Parents picking up their children at Grimes Elementary School Thursday were shocked to hear about the violent attacks, especially on the younger girl walking home alone. 

"It's scary, it's really scary," said Priscilla Brinkley. "Being the mother of children so young, and nowadays parents have to work to support their children and they expect children are going to be safe in this area." 

"That's a wake-up call for a lot of these parents," said Robin Mitchell. "You have to monitor your kids and just watch your surroundings."

-- Michael George contributed to this report