A 5-year-old girl suffered a gunshot wound in her upper body after her 3-year-old brother accessed an unsecured firearm in a southwest Washington, D.C., apartment on Monday evening, police said.

Metropolitan Police Chief Pamela A. Smith said that officers responded at approximately 6:30 p.m. to an apartment in the Unit block of Galveston Street SW for reports of a shooting.

“What we know at this time is the female victim was injured when a younger child accessed a firearm that was unsecured in the apartment,” Smith said.

The girl was administered first aid and transported to an area hospital in serious condition. She remained in critical condition, according to Smith.

A man, who was responsible for providing care for the children at the time the incident occurred, was inside the apartment and was arrested and charged with cruelty to children, police said.

A woman was also arrested and charged with assaulting a special police officer, who worked at the apartment complex, police said. Police said they believed the woman was the sister of the girl who was shot.

“What I want to emphasize tonight is that this incident really highlights the danger of unsecured firearms in homes and especially around children,” Smith said. “We want to emphasize the importance of firearm safety and we are asking everyone to keep our young female victim in your prayers at this time.”

Smith said the investigation remained ongoing and that the information provided at the press conference was preliminary and subject to change.