Where was this photo taken?
It’s a large white-headed gull and looks like a Lesser Black-blacked Gull, as do the others (at least one is an adult). Note the yellowish legs and overall darkness, but with the wingtips darker than the upperparts. Seems to be a 3rd year bird.
Assuming its in Florida, the main other alternative is that the photo has made them all artificially dark and that they are just Herring Gulls. However, that would not explain the yellowish tones on the legs.
The photo was taken mid-beach in Miami Beach