Washington: The man who shot five US troops in Tennessee suffered from depression, his family said Saturday, as investigators sought to determine the motive behind the rampage.
Four US marines and a sailor were killed when 24-year-old Mohammad Youssuf Abdulazeez opened fire on two military centers in Chattanooga on Thursday, before dying himself in a shootout with police.
"There are no words to describe our shock, horror and grief," his family said in a statement cited by an NPR public radio journalist.
"The person who committed this horrible crime was not the son we knew and loved," it added.
"For many years, our son suffered from depression. It grieves us beyond belief to know that his pain found its expression in this heinous act of violence."
Authorities have said they are treating the case -- a grisly scene reminiscent of other shooting rampages at US military installations -- as an "act of terrorism."
Investigators are looking into Abdulazeez`s travel abroad and activity on social media to understand why he carried out the attack.
Divorce papers filed by his mother also point to an unhappy home life, including allegations his father beat his wife and five children.
The Abdulazeez family said they would continue to cooperate with law enforcement and expressed their condolences to the families of the victims.