A five-year-old girl is fighting for her life after her three-year-old brother shot her with an unsecured firearm.

On Monday (December 16), the Metropolitan Police Department arrived at an apartment in the Unit block of Galveston Street SW, Washington DC, following reports of a shooting.

A three-year-old girl is in critical condition after being shot by her younger brother. Credit: Aydinmutlu / Getty

Upon arrival, authorities found a little girl who suffered a gunshot wound to the upper body after “a younger child accessed a firearm that was unsecured in the apartment,” per police report obtained by PEOPLE.

The little girl, who was not named, was administered first aid and transported to an area hospital in serious condition.

She remained in critical condition, Metropolitan Police Department Chief Pamela Smith disclosed at a press conference.

“The child right now is in critical condition. It’s such an unfortunate incident. We cannot talk about gun safety enough,” Smith said.

The cop said the shocking shooting is a reminder of the vital importance of gun safety. “Again, when we have firearms in our homes there’s an expectation that we are to keep our firearms locked up, especially away from our children,” she emphasized.

According to a preliminary investigation, the children’s mother left them in their apartment in the care of a family friend, 59-year-old Darrell Graham, who was present during the shooting.

He was arrested at the scene and charged with First Degree Cruelty to Children, ABC News reported.

A woman named D’Jaunae McCrory Jackson, 21 – who was identified by police as a sibling of the five-year-old girl – was also charged with negligent storage of a firearm, prohibited possession of certain dangerous weapons, first-degree cruelty to children, and other gun-related charges.

In addition to this, another person named McCrory Jackson was charged after allegedly assaulting a special police officer, who worked at the apartment complex, after they responded to the call.

Following the execution of a search warrant on the home, law enforcement recovered the ammunition and ghost gun used in the shooting.

United Against Gun Violence explained that ghost guns are “unserialized (and therefore untraceable) firearms that are put together by components purchased either as a kit or as separate pieces” but are “fully functioning guns”.

The investigation is ongoing. The police said the information provided at the press conference was preliminary and subject to change.