AZUSA (CBSLA.com) — Three people were found dead inside an Azusa home that was on fire Thursday afternoon.

Los Angeles County fire crews were called to a residence in the 500 block of Dalton Avenue around 2:45 p.m.

Upon arrival, firefighters saw that the house and its garage were already fully engulfed by the flames.

Authorities said they also heard the sound of ammunition “burning off” in the structure.

Neighbors in the area, who said the person who lived in the home was a gun collector, reported hearing bullets going off and “popping” sounds, as well.

Three adult bodies were discovered after the fire was extinguished about 4 p.m., according to Lt. Mike Bertelsen from the Azusa Police Department.

Bertelsen said officials couldn’t enter the home following the blaze because of a collection of guns inside.

“There are a few weapons that are inside and they need to make sure that those are handled appropriately after a fire has taken place,” he said.

The incident is being investigated as an arson.