Emblem3

Tonight's "X Factor" live show is being sabotaged by tuna sub sandwiches that left several contestants vomiting -- and now one's even been rushed to the hospital ... TMZ has learned.

Sources close to the production tell TMZ, Drew from the group Emblem3 went to the set, but had to be hospitalized within the last hour because he couldn't stop heaving up his guts. We're told he's currently on an IV drip at an L.A. hospital, and may not be back for the live broadcast.

We're told the vomit-fest started last night when a bunch of contestants and crew members ordered take out to their Hollywood Hills pad -- and almost everyone who ate the tuna salad subs were up sick all night. We'll spare you the details.

Total casualties: 6 crew members out sick, Camilla from the group 1432 is on set, but yacking non-stop ... and of course, Drew is down for the count.

The cocky guys from "X Factor" who make up the band Emblem3 were partying their faces off in Los Angeles last week ... so much so that the hotel they're staying in threatened to kick them out.

Emblem3 -- who made their name on "X" singing original songs (below) -- is made up of three guys, ages 15 to 19. We're told the boys threw a massive party in their hotel room this week partying, which included other "X" finalists.

According to our sources, it got so loud that hotel guests complained and called security ... who then shut down the party, and threatened to kick the boys out.

We're told "X" producers -- who are footing the bill for all the contestants -- had to swoop in and save the day, by begging the hotel to let them stay.

A source close to the show tells us, "All the partying Emblem3 is doing is distracting the other contestants and they've been warned to behave."

Teenagers. What are ya gonna do?