Husband allegedly fatally shoots wife, 3 daughters; son witnesses attack: Officials

A man allegedly shot and killed his wife and their three daughters in a domestic violence incident at their suburban Illinois home, but spared his 19-year-old son, who witnessed the slayings, according to authorities.

Maher Kassem allegedly shot his wife and three daughters "during a verbal argument" at their home in Tinley Park around 11:30 a.m. Sunday, according to police in Tinley Park, about 30 miles south of Chicago.

Kassem's 19-year-old son was home during the mass shooting and was not shot, according to the detention proffer.

The 19-year-old heard arguing in the basement between his dad, mom and older sisters, and then heard gunshots, according to the detention proffer. He then heard the arguing turn to screaming, the document said.

The teen went to the basement and found his mom on the floor and saw two of his sisters who appeared to be shot, the document said. The teenager then witnessed his dad shoot his third sister and shoot his mom, the detention proffer said.

The wife, Majeda Kassem, 53, was shot seven times, and the daughters -- Halema Kassem, 25; Hanan Kassem, 24; and Zahia Kassem, 25 -- were also shot multiple times, according to the detention proffer.

"Shortly" after the shooting, Maher Kassem called police and "reported that his wife had been shot," the detention proffer said.

A responding officer asked Maher Kassem "who else was there and the defendant stated, 'they're gone' 'everything is ok,'" according to the detention proffer.

Maher Kassem allegedly said there were "four people shot" and "I'm going to jail," according to the detention proffer.

When an officer asked Maher Kassem, "This was you?" he allegedly "nodded his head in the affirmative," the detention proffer said.

The "four innocent women," who all lived in the home, were killed in a "senseless" act of domestic violence, Tinley Park Mayor Michael Glotz said at a news conference Monday.

Maher Kassem was heard on police video saying, "I worked all my life to give my family a better home and they treat me like s---. They treat me like a dog," according to the detention proffer. He also allegedly said his "wife's worried about money and where she can take it," according to the document.

Maher Kassem, 63, was taken into custody and charged with four counts of first-degree murder, police said.

Tinley Park Village Manager Pat Carr said the shooting was an isolated incident and described it as a "traumatic scene for everybody involved."

"This is about family violence and the power of one person over other family members," said Itedal Shalabi, the co-founder and executive director at Arab American Family Services.

Police recovered a .38 caliber revolver and a 9mm semi-automatic pistol, according to the detention proffer.

Tinley Park Police Chief Tom Tilton said police had no prior interaction with the victims' house.

ABC News' Cheryl Gendron contributed to this report.