It all took place on the 3800 block of I Street in Juniata, right near Erie Avenue.
Investigators say a violent had argument erupted between 48-year-old Jake Harkin, Sr. and his wife, 41-year-old Jessica Harkin.
According to police, their 14-year-old daughter witnessed the fight, called police and locked herself in a room.
"Dad was having some type of physical altercation with mom, he then pulls out a gun and shoots her. He went into his son's bedroom, he's asleep, he takes the gun, fires one time at point blank range then turns the gun on himself," said Capt. James Clark.
When police arrived around 12:45 a.m., they heard four gunshots and ran in through the front door.
On the second floor landing officers found Jessica shot twice in the back of the head. She was losing a lot of blood and was rushed to the hospital.
Officers then discovered 10-year-old Jake Harkin, Jr. lying in bed, shot once in his head. He was pronounced dead at 1:14 a.m.
Harkin Sr. was found dead on the floor next to him - a handgun by his side.
Investigators say police have responded to domestic violence calls at the home in the past, and that Harkin Sr. is no stranger to police, with dozens of prior arrests for a wide variety of offenses.
"A lot of past domestic problems between the two. There was no domestic order in effect. At the end of the day it's very sad that she got shot and the 10-year-old died in his sleep," said Capt. Clark.
Jessica remains hospitalized in critical condition, but is conscious and talking.