I read this in a compilation of sci-fi stories in book form. The story starts off as a planet exploratory mission, but is told in the form of transmitted messages, with a small team on the planet and mission control inside the space ship orbiting the planet.
The exploration team encounters a primitive alien race and they have some festival/ritual and invite the team, which mission control approves. Later on the team transmits weird messages saying they should proceed with colonizing planet, and later lose the signal.
So mission control sends another team, and they discover the campsite of the first team trashed with blood everywhere. They meet up with the aliens and before mission control can say no, the second team gets invited to the same ritual. At the end of the day mission control gets the same weird messages and figure out its the aliens doing it so they quarantine the planet, or I think they bombard the planet.
I know, the way I summarize it is lame... but the story was pretty good, creepy vibes and all.