Ray Kelly: Nanny Yoselyn Ortega stabbed herself as children's mom walked in

In 30 minutes, the calm of the second floor collapsed into chaos.

Nothing seemed out of order about 5 p.m. Thursday when nanny Yoselyn A. Ortega rode an elevator with the children she cared for, Lucia Krim, 6 and Leo Krim, 2, said a woman who lives in the Krims' Manhattan building.

Ortega wore her usual blank expression, and the kids seemed happy, said Charlotte Friedman, who has lived 30 years on La Rochelle's seventh floor.

Half an hour later, the children's mother's bloodcurdling screams filled the halls of 57 W. 75th St. Friedman said she saw a hysterical Marina Krim break down in the corridor while holding her daughter Nessie, 3.

"She was bent over the child, screaming, holding on to the only live child she had," Friedman said. "She was traumatized. She was deeply traumatized. And those screams were definitely primal screams because they were not even human; they were very deep, dark screams."

Marina Krim discovered Ortega stabbing herself with a knife when Krim walked into the bathroom and saw Lucia and Leo dead in the bathtub, NYPD Commissioner Ray Kelly said Friday. Ortega has been with the Krim family for two years, Kelly said.

Friday, police continued to investigate the slayings. They had not yet interviewed Ortega, who was comatose in a hospital where she was being treated for self-inflicted stab wounds.

Authorities said the Krims were overcome with grief.

Ortega, a naturalized citizen from the Dominican Republic, has been in this country 10 years. She had been referred as a nanny to Krim and her CNBC executive husband, Kevin Krim, from another family.

Investigators were puzzled Friday about whether there was a motive to the killings or if Ortega had been suffering from a psychological or emotional problem -- and just snapped.

Kelly said there was some anecdotal reports Ortega may have visited a psychiatrist or that she wanted to do so, but that had not been confirmed.

Ortega was in critical condition at NewYork-Presbyterian Hospital / Weill Cornell Medical Center, where she is intubated and in a medically induced coma, Kelly said. She suffered mostly superficial wounds to her wrists and a deeper wound to the neck.

Asked if there was any possibility of someone else being in the apartment at the time of the killings, Kelly said, "I don't think anything is excluded at this time."

The tragedy unfolded when Marina Krim, who was returning from a swimming lesson with Nessie, went to their second-floor apartment because Ortega and the two children did not show up at a dance studio, Kelly said.

During the ride up the elevator, Friedman said she asked Lucia, "Are you going on a playdate?"

No, Friedman said the girl told her, they were all going home.

Friedman said she asked the girl what she was up to and said Lucia happily answered: "Dancing!"

Outside the building Friday morning, three tall candles were burning blue and white. Women with strollers approached the police crime scene tape to lay flowers in front of the 11-story building.

Later in the afternoon, police brought out bags of evidence, including a mattress-sized object, from the apartment.

With Kevin Deutsch

and Igor Kossov