Gunfire rang out near the home of Lost star Malcolm David Kelley this morning as cops apprehended a person suspected of breaking into his L.A. area pad ... while Malcolm was inside!!!!

Sources has learned the L.A. County Sheriff's Dept. received a call from Malcolm -- who plays Walt on the ABC show -- to report a burglary in progress at the actor's home in Bellflower, CA at 9:28 AM.

Sources close to the investigation tell us the bad guy first attempted to knock on the front door of the house -- and when no one answered, the perp tried to break in through the back.

We're told Malcolm heard the noise and immediately called 911.

When cops arrived to the scene -- we're told the bad guy tried to flee when he heard the sirens. We're told officers fired at least one shot at the suspect outside the home -- but no one was hit.

Eventually, we're told one person was taken into custody -- and is currently being detained.

Cops are still investigating the situation.

Malcolm's rep , Dominic Friesen, who tells us, "Malcolm and his family are incredibly grateful that no one was injured during today's incident."

He adds, "While it has been a frightening ordeal, the family is working closely with law enforcement on the case and applaud their quick response and efforts