NEW YORK (AP) — A nanny suspected of killing two young children she was looking after and then stabbing herself is in critical condition in a city hospital, as authorities continue to investigate the horrific episode that is a parent’s worst nightmare.

The children’s mother, Marina Krim, found her 1-year-old son and 6-year-old daughter stabbed to death in the family’s Upper West Side apartment Thursday evening. The children’s 50-year-old nanny was lying near them.

Their father, CNBC digital media executive Kevin Krim, had been away on a business trip.

Music therapist Rima Starr, who lives on the same floor as the family, said she heard screams coming from their apartment at around 5:30 p.m.