 In the aftermath of the Stuxnet worm that attacked Iran's nuclear facilities, there was speculation by security researchers working for Symantec that a number found in the Stuxnet code – "19790509" – which was used as a marker to identify computers that should not be affected, was a reference to his execution date; however, researchers also warned against using this possible connection to draw any conclusions as to Stuxnet's origin.On 19 January 2017, the 17-storey Plasco Building in downtown Tehran collapsed live on TV after a fire engulfed its top floors.Twenty firefighters were killed and at least seventy people were injured.