Nassau County police say 31-year-old Tommy Vladim Alvarado-Ventura, of Hempstead, was home with the 2-year-old daughter and 4-year-old son of an acquaintance, as well as another tenant who was watching the children while their mother was at work.
Authorities say the 2-year-old was heard crying as Alvarado-Ventura left the residence at 12:30 a.m. Tuesday, before he apparently headed to El Mariachi Loco bar on Fulton Avenue. There, he allegedly got into a fight around 2:20 a.m. that police say was unprovoked and with a female he did not know.
The 24-year-old woman with whom he was fighting reportedly tried to leave the bar, but police said he began punching and kicking her in the parking lot before stabbing her multiple times and slicing the inside of her mouth. Alvarado-Ventura allegedly fled, while the victim was rushed to the hospital with a collapsed lung.
After Alvarado-Ventura returned to the home, at 4:15 a.m., he and the acquaintance argued after police said the woman noticed severe injuries on her 2-year-old.
Police say Alvarado-Ventura punched the victim, then stabbed her. Despite her injuries, she was able to take her children to another area of the apartment and call police from a neighbor's once Alvarado-Ventura fell asleep.
When officers arrived a short time later, Alvarado-Ventura was taken into custody. He has reportedly a self-admitted gang member who has been deported four times and has an extensive criminal history, including possession of drugs, assault, resisting arrest, DWI and disorderly conduct.
WATCH: Police walk Alvarado-Ventura to vehicle
The victim and the 2-year-old were admitted to an area hospital, where it was determined the child was sexually assaulted and beaten around the head and face. Her injuries were so severe that she required surgery.
Nassau County Police Commissioner Thomas Krumpter called the incident one of the most horrifying he has witnessed.
"This is, in 28 years, probably the most heinous criminal act I've ever seen, and it really is nauseating," he said. "It doesn't usually affect us like that in law enforcement, but in this particular case, it's unprecedented."
Alvarado-Ventura is charged with predatory sexual assault of a child, attempted murder, assault and criminal possession of a weapon. He is being held without bail.