Yup - that's them. They'll leave you alone if you don't rile them up, but once they get going they're nasty as hell.
We had a huge nest in a shrub in our front yard a two summers ago, but we had no idea it was there. Our neighbor got stung while mowing the lawn after getting too close to the shrub, but we still didn't see it. A few days later, my wife pushed the mower right up under the shrub and got tagged 4-5 times. Of course, she's (truly) deathly allergic to bee stings and she didn't have an epi-pen on hand, so we had to call 911.
I went out the next day in about five layers of clothes and a makeshift helmet and sprayed the thing with a full can of wasp and hornet killer. Hit it again the day after that. After a few days, there was a pile of a couple hundred dead hornets on the ground, so I carefully removed the nest. Luckily, nothing in that nest was left alive.