▁Journal ' s ▁report ▁also ▁stated ▁that ▁a ▁man ▁said ▁that ▁he ▁sm elled ▁gas ▁about ▁thirty ▁minutes ▁before ▁the ▁explos ion ▁occurred . ▁Another ▁worker ▁reported ▁a ▁prop ane ▁leak , ▁and ▁shut ▁off ▁the ▁tank ▁and ▁issued ▁a ▁warning , ▁but ▁could ▁still ▁sm ell ▁the ▁gas . ▁The ▁Journal ▁interview ed ▁six ▁employees ▁who ▁said ▁they ▁were ▁never ▁formally ▁ev acu ated ▁because ▁it ▁would ▁have ▁led ▁them ▁through ▁the ▁Anne x ▁building . ▁ ▁At ▁ 8 : 0 7 ▁A . M . ▁Central ▁time ▁the ▁entire ty ▁of ▁the ▁dual ▁building ▁expl oded . ▁The ▁explos ion ▁happened ▁while ▁workers ▁were ▁performing ▁a ▁test ▁to ▁switch ▁to ▁a ▁back - up ▁system ▁he ating ▁system ▁which ▁used ▁prop ane ▁instead ▁of ▁gas ▁to ▁heat ▁the ▁facility . ▁ ▁The ▁explos ion ▁killed ▁three ▁people ▁and ▁injured ▁ 4 7 . ▁It ▁was ▁later ▁discovered ▁that ▁the ▁people ▁who ▁were ▁killed ▁were ▁attempting ▁to ▁repair ▁the ▁leak . ▁Deb ris ▁land ed ▁several ▁blocks ▁away ▁from ▁the ▁site ▁of ▁the ▁explos ion ▁and ▁cars ▁were ▁hur led ▁through ▁the ▁air ▁by ▁the ▁force ▁of ▁the ▁bl ast . ▁The ▁explos ion ▁caused ▁w ides p read ▁damage ▁to ▁an ▁area ▁approximately ▁the ▁size ▁of ▁two ▁football ▁fields . ▁The ▁Department ▁of ▁Ne igh bor hood ▁Services ▁later ▁carried ▁out ▁an ▁ins pection ▁of ▁the ▁site ; ▁they ▁discovered ▁that ▁buildings ▁within ▁a ▁radius ▁of ▁approximately ▁ ▁had ▁sust ained ▁heavy ▁damage , ▁such ▁as ▁torn - off ▁roof