Officials with the Orange County Sheriff's Department said gunfire erupted just before 4:30 p.m. at a house in the 18000 block of Manning Avenue in North Tustin.
There was also a 9-year-old boy in the residence, but he ran out and was not harmed, they said.
The 73-year-old man was pronounced dead at a hospital and the 16-year-old boy was in critical condition at Western Medical Center in Santa Ana.
Authorities said the woman was hospitalized with an undisclosed injury.
The Associated Press and City News Service contributed to this report.