Isaias De Jesus Valencia is a resident of Pomona, California. ^[1]

Valencia was known to suffer from mental illness. ^[1]

On Saturday March 10, 2018, Valencia was taken into custody after he allegedly shot and killed Gregory Casillas and injured another following a 15-hour standoff. ^{[undefined] [1]}

The incident began when police responded to the 1400 block of South Palomares Street at about 9:00 p.m. Friday March 9, 2018, to a call about a reckless driver.

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Responding officers found the vehicle and a short pursuit ensued when Valencia failed to stop.

He then got out of the vehicle after crashing and ran into an apartment complex in the area.

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Valencia then allegedly barricaded himself into a room inside an apartment and eventually shot through a door, wounding the two officers. ^{[undefined] [1]}