Police in Sweden say three men have been arrested on suspicion of being part a group rape that was streamed live on a closed Facebook group.

Police spokeswoman Lisa Sannervik says the investigation into "a serious sexual offense" was in "a preliminary phase" and she could not provide further details. No charges have been pressed.

Sannervik said Tuesday a teenager and two men in their 20s were arrested Sunday in the city of Uppsala, north of Stockholm, after police received tips about the ongoing streaming and rape from users.

Deputy Chief Prosecutor Magnus Berggren told Sweden's TV4 channel Monday investigators don't have "the footage showing the alleged assault," and urged anyone "with "access to this footage" to turn it over.