However, there were no arrests at West Ham, and no phones or computers were confiscated.
Wednesday saw manager Slaven Bilic and his players enjoying a scheduled day off. They weren't at the training ground or the stadium, while West Ham joint-owners David Gold and David Sullivan, and vice-chairman Karren Brady, were also not present when the raids took place.
Bilic did not comment on the incident on Thursday but instead found himself talking about the all-too familiar story of Andy Carroll being ruled out, with a groin problem sidelining the England striker from Saturday's league match at Stoke.
"I did expect him to be back for this game, but he should be for the next game against Spurs," Bilic said.