Jenelle Evans' Son Jace Hospitalized After Allegedly Pulling Gun, Threatening to Kill Grandma

Jenelle Evans' son Jace was placed in a mental health facility after a frightening incident involving a gun and his grandmother ... TMZ has learned.

Sources familiar with the situation tell TMZ ... Jenelle's mom Barbara Evans told the reality star Jace allegedly pulled out a firearm, put it to his head, and threatened to kill himself and Barbara.

We're told there were also concerns about possible substance use, with sources claiming Jace had been drinking and using drugs in the lead-up to the incident.

We broke the story ... law enforcement responded to a February 22 call at Barbara's North Carolina home for what authorities described as a "troubled teen disturbance," with 7 officers dispatched to the residence. Jace has been living there with his grandmother.

As we first reported ... Jace is now receiving professional treatment at a mental health facility. It's unclear how long he will remain in care, but those close to the family say the focus right now is on his health and stability.