Ruiz had apparently stabbed them in a fit of rage, police said. He then contemplated what to do with the bodies, and may have considered putting them in garbage bags, police said.
In the end, Ruiz decided to call the father of the children in the Bronx, who contacted police.
About 1 p.m., two plainclothes officers arrived at the home where Ruiz lived with this 22-year-old girlfriend and her two girls - ages 2 and 5. He answered, and they noticed the woman on the floor to his left, bloodied, partially wrapped in plastic garbage bags, Browne said.
The officers quickly arrested the 24-year-old Ruiz, who did not resist. When they searched the apartment, they found the girls, also believed to be stabbed, in the common area, wrapped in a carpet, tied, and shoved into plastic bags, Browne said.
A knife hasn't been recovered, but police were still actively investigating the scene, Browne said. The victims' names were not released pending family notification. Ruiz made statements implicating himself in the crime, Browne said. It wasn't clear if Ruiz had an attorney, there was no phone number listed for his father's address.
The couple lived together in the second-floor apartment in a three-story building for the past six months, police said. They were both unemployed, police said.
Investigators believe the woman and her children were stabbed after a loud, raging fight that started late Wednesday evening outside the home and continued inside. The fight was overheard by neighbors, police said. He spent a day with the three corpses in the apartment before calling his father Friday to confess, police said.
But there was no history of domestic violence at the scene, and police didn't have a motive in the crimes.