Sir Trevor Brooking, a West Ham legend, was at the match and he gave his thoughts to 'BBC Five Live'.
"A coin did hit David Sullivan. I didn't see it but I did have that confirmed," Brooking said. "That atmosphere must never come back".
Brooking believes stewards were not equipped to deal with the situation.
"The actual level of aggression was something I couldn't believe West Ham fans would get involved with," he added.
"A lot of the stewards who are on duty on matchdays are not West Ham people - they're actually stadium people and sometimes until they get a job there haven't had any experience dealing with football crowds.
"They were quite young and couldn't deal with the aggression they were faced with."
West Ham lost the game 3-0 and the fans were protesting about the football on the pitch and the direction the club is being taken off it. Fans invaded the pitch and captain, Mark Noble, was seen clashing with one of them who got too close to him.
Since the move to the London Stadium at the beginning of last season there have been frequent clashes amongst supporters in the stands and the level of stewarding has left a lot to be desired.