Wilfredo Rivera doesn't know why his brother shot and killed LAPD SWAT Officer Randal Simmons after first killing three family members, but he offered his condolences to the officer's family yesterday.

Rivera, 27, is married and does not live in the house where his brother Edwin, 20, killed his father Gerardo, 54, and brothers Edgar, 21, and Endi, 25, before calling 911 and confessing to the murders.

When the LAPD SWAT unit responded and entered the house, police say Edwin Rivera fired on officers and shot and killed SWAT Officer Simmons. Officer James Veenstra was shot in the face and is currently recovering at home following surgery.

Simmons' family says the officer received the fatal bullet when he stepped in front of Veenstra to prevent him from being shot a second time.

For his part, Wilfredo Rivera does not know what to make of what happened. He says his brother was depressed, but has no explanation for his actions. "The family is at a loss," Rivera told the L.A. Times. "We are grief-stricken."

Simmons' mother, Constance, told KABC TV she forgives the gunman because that is what her son would want.