A suicide note left by a US teen who went on a shooting spree at a mall in Nebraska has been released by police.

Robert Hawkins, 19, left the hand-scrawled note at the Bellevue house where he lived before going to Omaha's Westroads Mall on Wednesday with an AK-47.

He opened fire randomly in the Von Maur store, killing eight people before taking his own life.

It is the second mass shooting at a US mall this year.

The three page message left by Hawkins, which included a will, said that he had "just snapped". It conveyed love for his friends and family, but nothing but contempt for his random victims.

"I know everyone will remember me as some sort of monster, but please understand that I just don't want to be a burden on the ones that I care for my entire life. I just want to take a few pieces of (expletive) with me," Hawkins wrote.

The teenager said his friends would be better off without him, and told them to remember the good times they had.

"Just think tho I'm gonna be (expletive) famous," he wrote.

He was more apologetic on another page, addressed to his family.

"I've just snapped I can't take this meaningless existence anymore I've been a constant disappointment and that trend would have only continued."

He added, "I love you mommy. I love you dad."

Police have also released three surveillance images from the shooting.

They show Hawkins walking into the mall unarmed, and returning six minutes later with an apparent bulge under his clothing.

In the last image, he is shown with his sleeves rolled up, aiming the AK-47 to fire.

His victims included six employees and two customers.

Hawkins had lost his job and broken up with a girlfriend recently, and acquaintances said he was a drug user and had a history of depression.

Hawkins spent four years in a series of treatment centres, group homes and foster care after threatening to kill his stepmother in 2002, state officials said.

In August 2006, social workers, the courts and his father all agreed it was time for Hawkins to be released - nine months before he turned 19 and would have been required to leave anyway.

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