The two boys were in a "tug-of-war" over the gun when the 9-year-old stabbed the 11-year-old in the chest with a knife the child was holding.
Police said the man suspected of stabbing a lawmaker had previously been suspected of radicalization but was not on a watch list.
Norwegian police said that the suspect's apparent mental illness was the likely cause for the attack that killed five people.
The man arrested in the murder of Conservative lawmaker David Arness has not been identified as a terror suspect, but is being held on suspicion of murder.
The district court said Tamin Sultani used a kitchen knife from his apartment "because he was so upset" about something blasphemous done to his god.
The horrific attack took place on Tuesday in Central London's Hyde Park. The victim sustained injuries but is expected to survive.
The 29-year-old is facing attempted murder and other charges after also assaulting a fire lieutenant trying to administer first aid.
Police have cordoned off an area of the Basilica of Notre-Dame de Nice following the suspected terror attack on Thursday morning.
Vladimir Nachev, 18, stabbed Hakim Sillah with a 10-inch "Rambo"-style knife at a community center in London in November last year.
"He had knives in both hands and, upon seeing me with the narwhal tusk, pointed at his midriff," Darryn Frost told Britain's Press Association.
"He hit a girl in the neck with a sword and stabbed her in the stomach," a witness told the Keskisuomalainen newspaper.
Walmart security allegedly recovered $358.23 worth of stolen items from Doranda Jo Ussery before she launched the attack.
While violent crime in China is unusual and attacks on children even rarer, there has been a marked uptick in such incidents over the past decade.
He stormed the hospital after stabbing a 25-year-old outside.
Oscar Alvarez reportedly turned himself in to police hours after the attack.
In China, the suspect has been detained and is in police custody.
The Somali attacker had criticized the media for its portrayal of Muslims.
Zakaria Bulhan also charged with five counts of attempted murder in Russell Square attack.
Police shot dead both assailants in Saint-Etienne-du-Rouvray.
The alleged assailant, a 27-year-old man who was under arrest and suspected of using drugs, shouted "Allahu Akbar" ('God is Greatest' in Arabic).
The latest knife attack in the country left two children seriously hurt.