Details are still coming in, but this much we know, according to a Perez Hilton source:
The ex-American Idol finalist got into a "huge fight" with boyfriend Sauli Koskinen outside of a bar in Helsinki called "Don't Tell Momma." Both were booked by local police and, as of early this morning, are sitting in separate jails in the area.
Adam Lambert and Sauli Koskinen
Finnish journalists claim that witnesses attempted to break up the brawl, only for Lambert to also attack the peace-makers. No one was seriously injured in the melee.
We'll have more on this arrest as news breaks. Lambert, meanwhile, is in the process of promoting the first single off his second album.
UPDATE: The duo has been released and Koskinen has blogged: "Publicity is not easy, but also celebrities are just human. Love is not easy either, but it lasts forever!"
[Photo: WENN.com]