The day after the accident, Jordan Baker calls Nick at work and tells him that she has left Daisy's house and gone to Hempstead. She tells him that she is heading to South Hampton. The conversation ends with Nick, more or less, that any relationship that might have existed between Nick and Jordan was now over.
Nick was preoccuped with thoughts of Gatsby, having spoken to him before he left to go to work. Nick tried calling Gatsby several times but the line was constantly busy.
Nick rushes home to West Egg and finds Gatsby dead, floating in the pool, having been shot and killed by George Wilson, who is also dead by his own hand.
With no servants in the house, just the bunch from Meyer Wolfsheim, Nick suggests that the chauffeur, butler and gardener knew that something happened to Gatsby, they must have heard the shots, but apparently disregarded them.
"The chauffeur, he was one of Wolshiem's proteges, heard the shots, afterward he could only say that he hadn't thought anything much about them." (Fitzgerald)
Wolfsheim's men are trained to mind their business, as members of his mob of goons, they don't get involved in the boss's business, they mind their own business, ignore sounds like shots, because they were probably taught to to so. If someone is being eliminated, you don't ask questions, you just follow orders.