▁order ▁to ▁break ▁through ▁the ▁v ault ▁floor , ▁van ▁Ste enberg h ▁first ▁tried ▁a ▁ham mer ▁and ▁ch is el , ▁but ▁quickly ▁realized ▁he ▁would ▁need ▁stronger ▁tools . ▁He ▁then ▁in quired ▁about ▁suitable ▁tools ▁at ▁a ▁tool ▁r ental ▁shop ▁and ▁was ▁shown ▁a ▁rot ary ▁ham mer . ▁He ▁broke ▁into ▁the ▁shop ▁the ▁same ▁night ▁and ▁st ole ▁the ▁tools ▁he ▁needed . ▁However , ▁the ▁power ▁tool ▁turned ▁out ▁to ▁be ▁so ▁no isy ▁that ▁van ▁Ste enberg h ▁fe ared ▁it ▁might ▁alert ▁others ▁to ▁his ▁actions , ▁and ▁tempor arily ▁abandoned ▁his ▁plans ▁over ▁Christmas . ▁In ▁early ▁January ▁he ▁decided ▁to ▁bl ast ▁a ▁hole ▁in ▁the ▁v ault ▁floor , ▁bought ▁dynam ite ▁under ▁an ▁assumed ▁name ▁and ▁studied ▁explos ives ▁at ▁the ▁Seattle ▁library . ▁In ▁mid - F ebru ary ▁he ▁began ▁to ▁dr ill ▁holes ▁in ▁the ▁v ault ▁floor ▁and ▁ign ited ▁his ▁first ▁round ▁of ▁dynam ite , ▁which ▁removed ▁only ▁some ▁five ▁inches ▁( 1 2 ▁cm ) ▁of ▁concrete . ▁ ▁Van ▁Ste enberg h ’ s ▁actions ▁did ▁not ▁go ▁entirely ▁un not iced : ▁employees ▁noticed ▁dust ▁and ▁pl aster ▁falling ▁from ▁the ▁ce il ings ▁and ▁cra cks ▁in ▁the ▁walls . ▁Exper ts ▁were ▁consult ed , ▁who ▁sus pected ▁an ▁industrial ▁paper ▁cut ter ▁on ▁the ▁third ▁floor ▁of ▁being ▁responsible ▁for ▁the ▁damage ; ▁some ▁also ▁attributed ▁it ▁to ▁the ▁building ’ s ▁location ▁near ▁the ▁Bo eing