in a separate mass shooting on saturday in oakland , a man donned a bulletproof vest and killing three police officers after he had been taken into a murderous rage by an arguing with his sister over a telephone . according to court papers , joseph poplawski — 26 had recently been dishonourably discharged from the us marines — had been battling with his mother about the dog masturbating inside their house early on the nights when she threatened to evict him . and the argument escalated , she called the police . by the time a patrol car turned up at after 7am , mark poplawski , 23 , had armed himself with an assault rifle , a broad - arm grenade , a gun and several rounds of gunpowder .
In Pittsburgh a man shot 3 policemen.