massachusetts emergency management agency report states some cops showed lack of ` weapons discipline while hunting the tsarnaev brothers '
they fired at suspects without ` necessarily having identified their target '
also failed to appropriately aim weapons during april 19 , 2013 , shootout .
shortly after , one officer ` mistakenly fired on an occupied police vehicle '
later in night , another cop ` fired weapon without appropriate authority '
however , report praises response of medical personnel after bombings .
` every patient that was transported to hospital from the scene survived '
three people were killed in april 15 attacks - a further 264 were injured .