Two toddlers died early Thursday after a woman allegedly stabbed her grandfather, tossed one child out a window and then jumped from an 11th-floor South Shore apartment — leaving the other child scalded in a bathtub, Chicago police said.

Police are investigating the case as an attempted murder-suicide. They believe the boys are the woman’s children but haven’t confirmed that.

The 20-year-old woman and 2-year-old Johntavis Newell were found about 2 a.m. Thursday on the ground outside a high-rise in the 7200 block of South Shore Drive, police and the Cook County medical examiner’s office said.

Police have security video from the building showing the child and the woman separately falling to the ground within seconds of each other, police sources said. The woman struck scaffolding before she hit the ground, sources said.

Building security employees took officers to the apartment where they found 7-month-old Ameer Newell in a bathtub and a 70-year-old man with stab wounds and cuts to his face and body, authorities said. The child in the tub was scalded and had “lacerations to the head,” police said.

The man told patrol officers his granddaughter stabbed him before jumping out the window.

The infants were taken to Comer Children’s Hospital, where they were pronounced dead, police and the medical examiner’s office said.

Johntavis Newell died multiple blunt force injuries from the fall, while Ameer Newell died of injuries from an assault, the medical examiner’s office said.

The man and woman were hospitalized in critical condition at the University of Chicago Medical Center, police said.

“They’re still sedated so we have not been able to interview them,” police spokesman Anthony Guglielmi said Thursday night, adding that detectives have made contact with some family members.

A family friend said the woman and about 10 other relatives just last week moved out of their home in the 8800 block of South Parnell Avenue in the Auburn Gresham neighborhood.

Outside that home Thursday, the family friend — who asked to not be named — said the news of the boys’ deaths “broke my heart.”

“They’re a loving family,” he added.

The family friend said the deaths of the children weren’t the only brushes with tragedy the family has endured in recent years.

In the summer of 2018, he said, three members of the family — including the woman’s brother — were shot and wounded outside the Parnell Avenue home.

Reached by phone Thursday morning, the woman’s brother declined to talk about what happened.

Contributing: Sun-Times Wire