INDIANAPOLIS -- A 13-year-old boy jumped naked into his foster mother's lap Friday morning and told her that he had just stabbed her pregnant daughter and grandson, police said.

The boy used a kitchen knife to stab Anastasia Jacobs, 19, multiple times and her son, A.J. Witherspoon, 2, at least once just before 8:30 a.m. at their home in the 6000 block of East 43rd Street, police said.

Jacobs stumbled downstairs and collapsed near the kitchen. She was listed in stable condition at Wishard Memorial Hospital Friday evening. Witherspoon, who suffered cuts to his leg and finger, was treated and released, 6News' Jack Rinehart reported.

The boy, who has been a ward of the state since he was age 5, had been living in Glory Jacobs' home for five months, police said.

Investigators said the victims were asleep in an upstairs bedroom when the boy attacked them.

Glory Jacobs told police that she and the boy had been watching television before 8 a.m. when he left and returned five minutes later without clothes on.

"He came back in the room naked and grabbed her, hugged her and said, 'I killed Ana,'" said Indianapolis Metro police Sgt. Matt Mount. "Within seconds, Ana walked into the room."

Anastasia Jacobs was covered with blood when she told her mother what had happened, police said.

The boy was taken into custody and will be charged as a juvenile with attempted murder and criminal recklessness, police said.

Family members told police that the boy had not been violent in the five months he had lived there.

"He gets kind of disrespectful sometimes, but you would never think he would do anything like this," said Audra Jacobs, Anastasia's mother.

The boy was set to move to another home in Fishers this weekend, family members said.

"He told me he didn't want to go no more because he was scared of people hurting him," Gloria Jacobs said. "I don't have authority over him."

Investigators said they are trying to determine a motive in the stabbing.