Yankee Stadium started implementing extra security Tuesday.
Anyone who enters the ballpark through certain gates will now have to walk through full body metal detectors or be wanded.
Yankee fans told News 12 that they received an email prior to Tuesday's game, explaining that they should arrive early because the entry process will take more time.
The email states that the increased security is part of a new initiative ordered by Major League Baseball, which requires all stadiums to get metal detectors by 2015.
Fans say that it is best to remove keys, cellphones and other metal objects before stepping through the detector.