Three of the four victims of the deadly beatings on the streets of Chinatown over the weekend were identified Monday.

The city medical examiner said 83-year-old Chuen Kwok, 55-year-old Nazario Vazquez Villegas, 49-year-old Anthony Manson, and a fourth victim who was not identified as of Monday night suffered head trauma, skull fractures, and brain injuries.

Randy Santos, 24, was arraigned Sunday afternoon on four counts of murder and one count of attempted murder in Manhattan criminal court.

(Randy Santos, the man police said beat four homeless men to death in Chinatown over the weekend, at his court appearance Sunday.)

Police said Santos used a metal pipe to bludgeon five homeless men over the head Saturday morning in Chinatown.

Four of the men were killed. The fifth was hospitalized with serious injuries.

Police say Santos is also homeless, and was arrested shortly after the deadly beatings while still holding the murder weapon, which was covered in blood and hair.

NY1 learned that Santos has been in and out of shelter for years. Police told us he had six prior arrests, at least one of them for assault.

Prosecutors say they have surveillance video of the attacks.

Santos allegedly admitted he is the man seen in the footage.

His attorney would not comment on the case.

Santos was being held without bail. A grand jury will hear his case on Friday.

Dozens of community leaders and elected officials gathered in Chinatown on Monday to mourn the victims and to call for action.

"This must be a loud and important wake up call to all of us," said Democratic Assemblywoman Yuh-Line Niou of Manhattan.

It comes as the city dispatches more mental health outreach teams to provide emotional support for the homeless and connect them to social services.

Mayor Bill de Blasio says experts are being deployed to the area in an effort to prevent another attack like this.