Will Tetra fish eat Guppies?

I bought 3 tetra fish and 3 guppies. The guppies are a lot smaller than the tetra fish. This morning I saw the tetra fish going after one guppy. This guppy is blue and has a big tail. The tetra ate chunks of the guppy's tail right off! Should I take them out? They are leaving the other two guppies alone. I fed them twice, and they seem agitated, they keep swimming for food. When I first got them they were all pretty calm in the tank. Please help!