As his friend asked him why he was holding the simulator, it suddenly detonated.
Police arrived at the Glendale home after calls poured from neighbors who reported hearing a loud explosion.
Officers reported seeing blood splattered on the front door and drops on the ground, but were unable to find Jusay because residents had already rushed him to Glendale Memorial Hospital.
Emergency doctors treated him and transferred him to another local hospital that same day, Glendale Memorial spokesman Jae Chung said.
Calls to Jusay’s Los Angeles home were not returned Monday.
Jusay told police that another friend in the Army National Guard gave him the simulator to him, but later recanted.
Glendale Police Sgt. Tom Lorenz said possessing the grenade simulator is a felony.
“We will be conducting a criminal investigation should he be found in illegal possession, or a person is stealing these from the government,” Lorenz said.
All weapons are locked away and removed only for training and military action, which are closely monitored, a spokesman for the National Guard said. A grenade simulator is used for field exercises in military training.
“We don’t let soldiers take them home and share them with friends,” 1st Lt. Will Martin said.