Camping when invaded by a buffalo herd

We had many exchange students and one we had from Norway had camped a lot in Europe with her parents so we decided before we sent her home to show her the USA. Ray had been in the Field artillery in Oklahoma and knew there was a state park near the camp so off we went and reached Oklahoma the first night. The Buffalo were off in a pasture and we checked into the campground. We were awakened by the sound of buffalo and they went through the campground headed for a lake. The rangers did not want them there and used a helicopter to drive them back to their pasture, right back thru the campground. We heard them and all got into the car in time. They did not knock down the tent but stopped and licked the clothes on the clothesline. Ingrid was frightened as all of us were and we kidded her about Norwegians being very brave and discovering the world and her answer was they did not send the women.