Shortly before Ikaris...
... pushes Ajak off the cliff...
... he mentions that the Deviants killed a company of oil workers.
IKARIS: It’s just up ahead. They must have been trapped in the ice for centuries and broke free last week when the glacier started to melt as the Earth’s core heats up for the emergence. They killed an entire company of oil workers. I tracked them here.
Eternals (2021)
The opening shot of the scene in Alaska shows some manmade structures you'd associate with an oil field.
This shot shows one of the Deviants tugging on what looks like a bag of some kind.
You can see some oil pumps near the top of this shot.
And there's a damaged snowmobile in the bottom-right corner of this shot. The snowmobile is also visible in the third image, near tracks on the ice, leading toward the oil pumps.
Given all theeverything above, it appears that the spot where...
... Ajak was killed by the Deviants...
... is the same place where at least one of the oil workers was also killed, and some of their belongings -- including the gun and the snowmobile -- were left scattered aroundstrewn across the areaice.