NASHVILLE — A 2-year-old shot and killed her 7-year-old cousin Tuesday in an apartment southeast of downtown.

Metro Nashville police have not yet indicated whether they will file charges in the shooting, which happened shortly after 12:30 p.m. CT. Harmony Warfield, 7, was taken to Vanderbilt University Medical Center with life-threatening injuries and was later pronounced dead.

It was not immediately clear where the toddler obtained the weapon or whether it had some sort of locking device.

In a fatal accident 2½ years ago, a Spokane, Wash., gun-shop owner considered another 2-year-old's shooting of his mother highly improbable because many firearms require at least 5 pounds of pressure for a trigger to work. Older guns may require half that.

► 2016: 2-year-old finds gun in back seat, fatally shoots mom
► 2016: Toddler son shoots mom from backseat; she survived

But a typical 3-year-old boy has a grip strength of about 1 pound per square inch, according to a study published in The American Journal of Occupational Therapy more than 20 years ago.

And a typical 2-year-old doesn't have a large enough hand to grip a gun, Robin Ball, owner of Sharp Shooting Indoor Range & Gun Shop, said in December 2014.

Harmony's aunt, Dumonique Batey, 21, said the girl was "an angel."

► 2015: 2-year-old boy kills himself with father's gun
► 2014: Gun expert surprised that tot was able to fire pistol

"Harmony was a sweet, helpful child," she said. "She loved reading and she smiled all day, every day."

Batey said she wasn't at the J.C. Napier Homes apartment when her niece was shot.

Tamika Rucker's young son regularly played with Harmony although he wasn't there when the shooting took place. 

► 2014: Toddler reaches into purse and gun goes off, killing mom
► 2013: Toddler shoots Tennessee deputy's wife in unguarded moment

Rucker lives just across a small courtyard from the apartment where the child was killed.

Harmony would always run up to her for a hug or a Popsicle and take turns riding her son's battery-powered motorcycle, she said.

"It hurts," Rucker said. "I'm very sorry that happened to her mother."

► 2013: 4-year-old kills 6-year-old in New Jersey

Rucker also had trouble understanding how a toddler managed to lift a gun and pull the trigger.

"It's not easy being a mother," she said. "Watch your kids because stuff happens so fast."

Follow Ariana Sawyer on Twitter: @a_maia_sawyer