Early Monday morning, Michelle posted a photo of Brielle in a hospital bed and explained she was involved in a "terrible skateboarding accident and is in the ICU on life support."

She wrote, "She suffered a serious brain trauma and a fractured skull. She is in a medically induced coma to relieve pressure in her brain. She is in amazing hands up at Primary Children’s Hospital. Please- I am asking for prayers."

Michelle asked for people to pray and send well wishes, saying, "as a desperate mother, I am begging you to do so" because Brielle "needs support and healing right now."

"This is the worst experience of my life," she wrote. "ALWAYS MAKE THEM WEAR THE HELMET. ALWAYS. EVEN WHEN THEY PUSH BACK."

The 39-year-old thanked her neighbors, who found Brielle and called an ambulance. "You will never understand. I would not have found her in time. My heart is forever grateful," she wrote.

Michelle concluded her caption, "Thank you to all of you who have sent prayers and messages and love. Brielle has been through so much already this year. She has proven how strong she is. I know she will pull through. #PrayForBrie"

Fellow Bachelor Nation members poured out their support for Michelle and her family. Emily Maynard, who appeared on Brad Womack's season of "The Bachelor" with Michelle, wrote, "Oh Michelle I’m so sorry. Im praying for a miracle for you and your sweet girl. Sending you all the love in the world."

Ashley Spivey, also on Season 15, added, "Michelle - if anyone deserves a miracle it is you. I love you so much lady and Brielle will get thru this!"

JoJo Fletcher wrote, "I am so so sorry. Sending so many prayers to you and your sweet girl."

Later on Monday, Michelle posted a video of herself tearfully speaking about the experience and the fact that she is alone because only one parent can be in the room at a time. "It's really hard to be alone during something like this," she said. "Your prayers and your messages mean so much to us."

Michelle revealed Brielle is in surgery "removing fluid from her brain because her brain has so much swelling." She said in her video, "This is my worst nightmare. No mother should ever have to go through this."

Michelle wrote in her caption of the video, "I’m a mess. She is doing well. Stable and pushing. This surgery will be very helpful. Thank you for the prayers. We feel them. We see them working."