The activities of the gun lobby conference continue in the American city of Houston, 3 days after the massacre of Yuvaldi Elementary School in Texas, in which 21 children and a teacher were killed.

The National Rifle Association conference continues until Sunday at a large convention center in downtown Houston, Texas, where gun opponents are demonstrating outside, and one of them holds a sign reading "Our hands are covered in blood."

US citizen Keith Gillen says the Texas school shooting is "disgusting", but "the gun can't be blamed" on the perpetrator.

"We've always had weapons in this country," adds the retired Postal Service employee, noting that he owns more than 50 weapons.

Gillin stands in line to watch former US President Donald Trump speak at the National Assembly of the Gun Lobby in Houston.

Gillin, who wears military trousers and a hat that reads "Trump", says that the massacre "disgusted him", but that the problem for him "does not lie in the acquisition of weapons."

He explains that things would have taken a different turn if the people at the school had been armed.

Gillin asserts that "killers do not fear the judge or the police," so they should fear the victims they target.

The Gun Lobby Conference will continue in Houston until Sunday (Getty Images)

Our hands are stained with blood.

The activities of the National Association of the Arms Lobby Conference will continue until Sunday at a large convention center in downtown Houston, where opponents of arms are demonstrating outside.

One of them holds a sign that reads, "Our hands are stained with blood."

Trump received a standing ovation during the conference when he recited the names of all the children who died, describing them as victims of a "crazy" out of control person, before returning to point out that efforts to control gun ownership were "strange."

The former president criticized Democrats for "demonizing" "peaceful and law-abiding" NRA members.

"This is not Australia."

Hundreds of weapons are displayed in the conference halls, including pistols and semi-automatic rifles, including the AR-15S rifle used by the Yuvaldi school shooter, as well as clothing, hunting equipment and rifle accessories, including long-range scopes.

"All efforts to disarm Americans are doomed to fail," said retired police officer Rick Gamon, as he peers into a space where black semi-automatic rifles are displayed.

"This is not Australia, you can't take guns from people," says Gamon, 52, as he checks out one of the "appropriate" weapons to put behind his car seat or in his home safe.

Australia implemented strict gun laws after the 1996 Port Arthur massacre, which killed 35 people.

However, the United States, whose constitution provides for the right to own guns, failed to take measures to reduce armed violence, despite the fact that it witnessed several shooting incidents.