Inside Soap Star Hunter Tylo's On-Set Collapse

Queens of Drama star Donna Mills filled ET in on what went down during co-star Hunter Tylo's apparent collapse.

"We were doing interviews for our sizzle reel," Mills told ET. "Most everybody had done theirs already. I was directing the segment. Hunter was doing hers and doing a fabulous job as she always does. All of sudden she just collapsed."

NEWS: Donna Mills & Vanessa Marcil Clash on Queens of Drama

When Tylo went down, the cast and crew off camera initially thought that Tylo fell on purpose but quickly realized that something was wrong.

"We were all like, 'What happened? Did she decide that that was a good ending to her monologue?'" Mills said. "We were so shocked. We really didn't know. And then she didn't get up."

Mills said there were no warning signs to suggest Tylo wasn't feeling well beforehand.

NEWS: Genie Francis Returning to General Hospital

"She looked beautiful," Mills said. "She seemed totally in control of everything. That's why it was such a shock."

Despite efforts to contact her, Mills hasn't seen Tylo since the fall and no one knows what caused the collapse or the injuries she may have suffered.

"She's been somewhat aloof," Mills said. "She is a very private person and wants to recover on her own."

NEWS: Stars Give Us Their Best "Dramatic Soap Face"

Queens of Drama, which airs Wednesday night on Pop, follows a group of former daytime and primetime actresses as they try to pitch a new series with the hope of landing a pilot deal by the end of the season. The show also stars Vanessa Marcil, Joan Collins and Lindsay Hartley.

Kylie Jenner Sizzles in Jacuzzi Bikini Shoot
Brooke Burke & Her Look-a-Like Daughter Pose in Bikinis
Diane Kruger Drops Her Top for Summer Sun