HARLEM, Manhattan (PIX11) — Thirteen-year-old Garrett Warren was witnessed pushing 11-year-old Alfa Barrie into the Harlem River before slipping and falling in himself, police sources told PIX11 News.

Another boy witnessed the incident happen and told police the boys were roughhousing when they fell in, according to law enforcement sources.

PIX11 News previously obtained photos of a broken fence that leads to the Harlem River shoreline, not far from the 145th Street Bridge where the boys were spotted on surveillance video the evening of May 12. A third youth was seen with them, police sources said.

The NYPD searched the Harlem River the same night after receiving 911 calls about the boys being in the water, but police did not find them.

Barrie’s body was discovered on Saturday in the Hudson River near 102nd Street and Riverside Drive. Two days earlier, the body of Warren was pulled from the Harlem River near the Madison Avenue Bridge.

The medical examiner said Warren died from accidental drowning, but the office reserved a determination on Barrie’s cause of death until it consulted further with detectives. Many are puzzled as to why Barrie’s body was found on the west side of Manhattan in the Hudson River.

Barrie’s family said they didn’t know how close the boys were because they went to different schools and lived in different boroughs.

Barrie lived in the Bronx but attended Democracy Prep charter school in Harlem. Warren lived in Harlem but attended NEST+M school in Lower Manhattan.