Arsenal moved back within two points of leaders Liverpool as headers from centre-back duo William Saliba and Gabriel, Saka's 41st-minute penalty and a fine Leandro Trossard strike put them 4-0 up at the interval.
Thousands of West Ham fans streamed out at half-time and opted not to return. In their absence, Saka scored again on 63 minutes before Declan Rice fired in a superb 25-yard effort and refused to celebrate against his former club after moving across London in a £105 million ($133m) move last summer.
"We were 4-0 up in the first half and we could have scored many more, including myself," Saka told Sky Sports.
"I think we smelled blood today and went for the kill. We did really well to score more and we were really happy."
In recording their biggest-ever away win in Premier League history, Arsenal backed up last weekend's win over Liverpool to move within two points of Jurgen Klopp's side and level with Manchester City, who have a game-in-hand.
Asked whether Saka's comments were indicative a team ready to hunt down their title rivals, Arteta told a postmatch news conference: "What I smell is a team who wants to be better and better. The way they trained this week, they were totally focused the day after Liverpool to say 'OK it is a big task and now it is time to go another level and beat West Ham' and they certainly did that today.
"We are maintaining and building some momentum now and the performances, they have been really strong as well as the results and we need to maintain that because we are not the only ones.
"We know the standards and the level we are facing and we need to be at this level if we have any chance to be successful."