3 lugs on one rim, safe?

Ok, so as I was installing the last rim on my car I was taking off the stock rims and as I was taking off the last lug (it was pretty stuck), all of the sudden (as I was putting on pressure) it cracked off! I was like ohh S&^T! I still went ahead and put the rim on, but only attached 3 lugs. I tried putting the 4th but it wouldnt go on. What I want to know is, is it safe to drive with 3 lugs attached? All the others are fine and have thier 4 lugs. If you are confused, please see the attached picture. Notice that there are only 3 lugs.