Selena Gomez reportedly "flipped out" when she discovered Kylie Jenner was texting boyfriend Justin Bieber behind her back, Hollywood Life reports.

The "Come & Get It" singer unfollowed the reality star and her sister Kendall on Instagram and cut them out of her friend group after discovering texts and photos from Kylie on The Biebs' cell.

"Kylie sent sexy pics of herself to Justin and thats what started the fight. Selena saw the pictures on Justins phone and she freaked out and left immediately," a source told the site.

    "Selena flipped out and there was a huge fight between the girls. She now wants nothing to do with Kylie or [her sister] Kendall," another source told Radar.

Depending of who you believe, the feud might already be over, though!

    "Selena has no issues with the Jenner girls. They had an issue but they have cleared it up. She has always liked the Jenner girls. They had been fans of Selena since they were young," a source countered to Us.

Now Bieber fever is causing cat fights!