On September 10, 2017, the 111th day of the battle, Sandoval was killed in action attempting to rescue one of his men wounded in a firefight with the jihadist militants.

[4] In August 2017, he had saved a group of Scout Rangers who had been trapped in a building in the main battle area.

The building, a 5-storey commercial complex called C&D Centerpoint, was occupied by a branch of the Land Bank of the Philippines prior to the siege.

After clearing the fifth to the second storeys, they were about to enter the ground level when a burst of gunfire wounded Corporal Jayson Mante.

His two other companions managed to quickly withdraw to the safety of the building's second storey, but Mante's injury prevented his own escape.

He ordered his men to provide suppressive fire while he and another soldier, Private First Class Sherwin Canapi, attempted the rescue.