The mother of a Mount Vernon man who died while being chased by police is searching for answers about why her son died and also why four men were shot attending a vigil for her son.

Iraida Sanchez is drowning in grief. Two weeks ago, she got the news that is every mother's nightmare - her son, 21-year-old Louis Rafael Rivera Sanchez had died. She says it happened at the East 180th station in the Bronx. "All I know is there was a chase, and then he was running from the cops, and then my son jumped, slipped and fell, and he hit the third rail," says Sanchez.

The funeral for Louis was held Tuesday and, later in the day, friends and family gathered in front of the family home at 333 South 8th Avenue in Mount Vernon for a candlelight vigil.

During the vigil, gunfire erupted and four people were shot. According to police, three men suffered non-life-threatening gunshot wounds but one victim was shot in the head and is in critical condition

Investigators say all four victims are from New York City.

Mount Vernon police are working with several law enforcement agencies to track down the shooter or shooters.

Sanchez says she is against gun violence and the shooting during her son's vigil only causes more pain. "I buried my son the day the shooting happened, they were here for my son. I don't know what could have happened, something prior, it could have been anything."

She says while she feels terrible for the families of the victims, she wants people to understand the shooting is a separate incident and she's just focusing on what happened to her son.

She tell news 12 that although she is being told her son died from electrocution...the medical examiner has listed the cause of death as undetermined. "I need to understand why my child died."

Mount Vernon police are asking for the public's help on this and they say tipsters can remain anonymous if they call police at (914) 665-2500.