DIAGNOSIS That's an out-of-balance load. The washer is trying to spin at high speed, but the clothes are all clumped on one side, making the drum wobble violently against the tub.
FIX 1) Stop the cycle and open the door. 2) Redistribute the clothes evenly around the drum. Don't just fluff them—actually spread them out. 3) Close the door and press Start. It should re-balance and spin quietly. For future loads, mix large items (like towels) with smaller ones, and don't overload past the top of the drum.
IF THAT DIDN'T WORK If the noise is more of a constant grinding or rumbling, even with no load, the suspension rods or shock absorbers that steady the drum might be worn out. That's a more involved repair.
HEADS UP Never try to stop a violently shaking washer by forcing the door open mid-spin. Let it finish its error detection and stop on its own, or unplug it if you must.