The Weeknd, Travis Scott, Swedish House Mafia, Tyga Spotted At Same Vegas Hotel

If you were at the Encore in Vegas Saturday, it looked like the TMZ Celebrity Tour, because The Weeknd, Travis Scott, Swedish House Mafia and Tyga all showed up in the same lobby!!!

Travis was the first to show at around 4 PM ... the father of Kylie Jenner's 2 kids was hangin' alone. He kept his head down to avoid the crowds and then disappeared.

A short time later, Tyga showed up in the same lobby with bodyguards and beelined it for the valet. He caused a little commotion as several women lasered in for his attention. Kylie's ex then drove off.

And then just a few minutes later ... The Weeknd got out of the elevator and walked over to the guys from SHM, hugging them and shaking their hands and then chit-chatting for a few minutes. He left with model Simi Khadra.

The Weeknd had a job to do that night ... he headlined at the Allegiant Stadium for his After Hours Til Dawn Tour.

Travis showed up for The Weeknd's show in Vegas, he was also there the night before in Denver. Tyga was also at the concert and watched from the Wynn field club in Allegiant stadium.

Swedish House Mafia also had a big night, kicking off their residency at XS nightclub at The Wynn -- one of the best selling shows in venue history. The Weeknd was in attendance after his concert.

The Weeknd's Saturday night concert was not without incident ... a fire erupted outside the venue at around 11 PM as fans were leaving.