Safety questions will be asked how supporters managed to smuggle in three smoke bombs and then throw them on the pitch and close to the away fans. With heightened security because of the terrorist threat, all supporters are searched on the bridges approaching the London Stadium island so it surprising these bulky items were not detected.
It is on offence for a person to enter or attempt to enter a football ground while in possession of a flare, smoke bomb or firework. The sentence for these offences can be as much as three months in prison, and in many cases, fans who have no previous convictions are being given prison sentences for attempting to enter a football ground with a smoke bomb in their pocket as the courts take these 
offences very seriously.
It appears a supporter in the West stand in either block 112 or 113 was able to bring in pyrotechnics undetected and launch them in the air when a West Ham chance was ruled offside. One of the smoke bombs seemed to strike a police or security officer before hitting the ground.
While the perpetrator is sure to be identified, arrested and banned once CCTV footage has been reviewed security questions must be asked of the Stadium operator as to how the supporter managed to get the devices into the stadium and what can be done in the future to prevent further pyro incidents.
Smoke bombs thrown towards Spurs at the London Stadium pic.twitter.com/Y5ysBeOmih
— West Ham Football (@westhamfootball) October 20, 2018