A toddler is believed to have fatally shot his mother in their California apartment, police in Fresno said on Monday. 

The 2-and-a-half-year-old boy was at home with his 18-month-old sibling, his 22-year-old mother and his mother’s boyfriend when he got ahold of a gun, Lt. Paul Cervantes said during a news conference. The gun belonged to Andrew Sanchez, Jessinya Mina’s boyfriend, officials said.

“At some point in time while handling that particular weapon, the toddler was able to manipulate the trigger, and it actually struck Mina as she was lying in bed,” Cervantes said. 

She was shot in the upper body, police said. The mother of two was taken to a local hospital for treatment, but she didn’t make it. 

“It’s devastating and definitely serves as a stark reminder of the significance and importance of being able to properly store your weapon,” Cervantes said. 

Police said they were planning to spend the evening out and were relaxing at home when the shooting happened.   

Authorities said Sanchez left the loaded 9mm gun, which did not have an external safety feature, in the bedroom, in an area accessible by the children. He was taken into custody after the Friday shooting and was charged with felony child endangerment and felony criminal storage of a weapon. Sanchez was later released on bail. 

Sanchez is not the father of either of Mina’s children, police said. Both of the children are with Mina’s parents. 

In a statement to CBS News affiliate KGPE, Mina’s older sister described her as a beautiful soul. 

“My niece and nephew will have to live off of memories and stories of my sister rather than her presence,” the sister said. “We will never be able to witness my sister carry out her lifelong goals and accomplishments due to his negligence.”

Sanchez does not have a criminal history or any gang ties, police said. It wasn’t clear why he had a gun. 

California has some of the strongest gun laws in the country, including gun storage laws. 

Earlier this month, a 7-year-old boy fatally shot his 2-year-old brother after he found a gun inside a truck glovebox, according to officials in California’s San Bernardino County Sheriff-Coroner Department. Nationwide, there have been at least 288 unintentional shootings by children this year, according to the nonprofit Everytown for Gun Safety. Those shootings have resulted in more than 100 deaths and around 200 injuries.