Isidro Zavala, a Mexican living in Boynton Beach, allegedly strangled his 12-year-old son Eduardo with a rope and shot his 11-year-old son Mario, police said.
Zavala's estranged wife, Victoria Flores Zavala, attempted to stop him and pleaded with him to kill her instead, the South Florida Sun Sentinel reported.
"She said, 'Why don't you kill me?'" Detective First Grade Chris Crawford, the lead investigator, said at a news conference at the Boynton Beach Police Department. "He said, 'No, you're going to have to live with this.'"
Zavala, 45, killed himself with two shots and left behind a note to the couple's 19-year-old son, who was not living in the home and is alive.
Police said the motive for the 2 a.m. Saturday killings was unclear, though Zavala's wife filed for divorce in October.
Neighbors told the Sun Sentinel they were stunned by the slayings and said the family seemed quiet and hard-working.
But kids in the neighborhood said the two victims seemed afraid of their father.