An armed citizen was captured on camera holding a bloodied knifeman at bay just moments after he murdered his girlfriend in front of their five-year-old son.

David Lee Morris, 29, was arrested after he allegedly murdered his girlfriend Gabrielle Maria Garcia, 28, in a busy Seattle food court in broad daylight.

But before officers arrived, it was Scott Brown who made sure Morris couldn't flee the scene.

A passerby captured the tense moment Brown kept his gun trained on Morris while another man begged him to put the bloodied knife on the ground.

Armed citizen Scott Brown was captured on camera holding bloodied knifeman David Lee Morris at bay just moments after he murdered his girlfriend in front of their five-year-old son

A passerby captured the tense moment Brown kept his gun trained on Morris as he waited for police to arrive

'Jesus Chris put his life on the line for you man, it ain't worth it,' the man can be heard screaming at Morris.

Brown then tells Morris to get on the ground and put down the knife, but he refuses.

Instead he continues to walk toward Brown, his arms wide open and the knife still in his hand.

The pair walk backwards together for minutes but Brown never lowers his gun.

'I just kept trying to get him to put down the knife,' Brown later told KCPQ. 'We just kept walking backwards and backwards and backwards.'

'I was looking around for police, security. The point was to hold his focus, there were people around everywhere.'

Brown said that Morris 'kept trying to convince me to shoot him', even telling him to 'make the shot count' and confessing he had just 'killed the only person I ever loved'.

Brown can be heard telling Morris to get on the ground and put the knife down, but he refuses

A security guard for the area then sprays pepper spray at Morris, who continues to walk away

But Morris then turns back toward Brown, who continues to keep his gun trained on him

Two men who appear to be security guards at the Seattle Center, which includes the city's famous Space Needle, then arrive and tell everyone to clear the streets.

One of them goes up to Morris and tries to pepper spray him, but he seems unfazed and tries to turn around and walk away.

But Morris then turns back toward Brown, who continues to keep his gun trained on him.

Seattle police finally arrive on the scene and scream at Morris to get on the ground. He falls to his knees and puts his hands in the air but suddenly decides to stand up.

'He wants to die!' one female bystander screams as Morris refuses to get back down on the ground.

The police then Taser him and he screams out in pain and falls to the grass.

Seattle police then finally arrive on the scene and scream at Morris to get on the ground. At first, he gets on his knees

But Morris suddenly decides to stand up and police repeatedly tell him to get on the ground

Morris is currently being held at King County Jail on $2million bail.

Morris confessed to police that he murdered Garcia and told them he thought killing his girlfriend would improve their son's life, according to the Seattle Times.

He told police he first thought of killing Garcia in April or May but hoped to 'rehabilitate' their relationship.

Garcia obtained a temporary protection order against Morris on October 9. It was reissued later that month.

She had already begun court proceedings for a parenting and child support plan in March, which was finalized by the court on October 17.

But the estranged couple met on Friday to take their son to the Pacific Science Center.

Morris told police he was 'trying to engage her in conversation about their relationship problems' but she continued to avoid the topic.

He pulled out his knife in preparation of killing her in the Science Center, but decided he wanted to talk to her more while they bought pizza for their son.

'He wants to die!' one female bystander screams as Morris refuses to get back down on the ground. The police then Taser him

He screams out in pain and falls to the ground as police run toward him and detain him

Morris then brought up their relationship again while they sat at MOD Pizza, but Garcia stood up and told him she was going to the bathroom.

He thought she was going to the bathroom to call her attorney so he 'decided it was time to kill her', according to the affidavit.

Morris said he plunged the knife in Garcia's throat several times because 'he knew the first penetration did not hit the jugular properly', according to the Seattle Post-Intelligencer.

A witness yelled at Morris while another ran to get towels and give Garcia first aid. A third witness threw a chair before Morris walked away.

Mike Carter, a manager of one of the restaurants in the food court, also witnessed the horrific scene with Brown, who is one of his employees.

Brown (pictured) said that Morris 'kept trying to convince me to shoot him', even telling him to 'make the shot count'

Brown, who was at the food court on his day off, turned to Carter and said: 'I have a carrier's permit and I'm carrying. Should I go over there?'

Before Carter had a chance to reply, Brown had already run off to help.

'He was in no way looking to harm the man,' Carter told the Seattle Times. 'He was just trying to keep the focus on him until police arrived.'

Garcia was rushed to a local hospital, where she died a few hours later from her injuries.

The couple's son was taken into custody and Seattle police are consulting with Child Protective Services on his placement.

Morris was still holding the knife and 'had visible blood on him' when police detained him at the scene.

Morris stabbed his girlfriend Gabrielle Maria Garcia, 28, multiple times in the neck at Mod Pizza (pictured in file photo) at the Seattle Center in broad daylight on Friday

Brown, who was at the busy food court (pictured in a file photo) on his day off, decided to help when he heard her screams

Authorities said he was 'very talkative' and told investigators in an on-camera interview that he believed murdering Garcia 'was best' for their son.

He thought he didn't have a chance to get custody of the boy and wanted to kill Garcia so their son could be raised by her brother while he was in jail.

'Morris acknowledged this may traumatize [the couple's son] if he remembers it, but he hopes he represses the memories'.

Carter hailed his employee as a hero for standing up to Morris during the horrific ordeal.

'Do you want someone who just potentially tried to kill his girlfriend - do you want that man's attention on you?' he said.

'The situation was handled so smoothly in the worst circumstances, and handled properly. Police came, the man was detained, nobody else was hurt.'

'We all pray for the victim, and the child, and the family, and everyone else,' he added.

'My heart weighs heavily for everyone who was hurt, both physically and emotionally.'