GREENWOOD VILLAGE, Colo. -- Authorities still do not know why a 36-year-old nurse jumped to her death from a moving ambulance on Interstate 25.

Melissa Lynn Watkins, of Aurora, was being transported as a patient from Parker Adventist Hospital to another hospital when she jumped out of the back of the ambulance, slammed on to the pavement and rolled to the side of the highway.

Other vehicles behind the ambulance were able to avoid hitting her. She died Sunday afternoon from her injuries.

Her family released a statement Monday, saying, "We are deeply saddened by the untimely loss of our beloved Melissa Lynn Watkins. The absence of her loving presence in the lives of all of her family, particularly her three young children: Madeline (9); Landon (7); and Michaela (4), and her husband, Ronnie, will be felt for all the years to come."

Her family did not want to talk about why she might have jumped, only saying that "To know Missy, was to know that her family and her faith were the center of her life. She was a very caring, Christian woman, who asked for nothing but gave greatly of herself to others. She will forever be cherished and remembered by all those who knew and loved her. She was such a beautiful reflection of God's love. Her time on this earth was far too brief."

Watkins was born in Lubbock, Texas, and held two degrees: a bachelor of science degree in cell and molecular biology from Texas Tech University and a bachelor of science degree from Texas Women's University, where she studied to be a registered nurse.

Greenwood Village police said Watkins jumped from the ambulance on her own accord, and was not pushed and did not fall out.

"The back door automatically opened like this and out (flew) the woman, maybe 10 yards or more. And she rolled and rolled and rolled, about 20 yards or more," said Edward Zapotoczny, a witness who was sitting in a car behind the ambulance. "It was very scary."

"I noticed a blurry object. I just thought it was some object that fell out of the ambulance. I didn't think it was a human," said Ed Sadowski, a driver. "Thank God we weren't directly behind because that would have been catastrophic."

An emergency medical technician and a paramedic with Action Care were both on board the ambulance when she jumped, authorities said. They were both shaken by what they saw and were given trauma counseling.

Every ambulance service has policies on when and how to restrain patients but what's still not clear is how the incident could have happened.

Action Care Ambulance said said she was strapped in a stretcher and that there was an EMT in the back with her. The company also said there was "a history involved" with Watkins, but didn't elaborate.

"There's a lot of questions to be asked," said Jaime Bosten, a risk manager for Pridemark, another ambulance service.

He said that Pridemark Ambulance always requires that the patient be restrained with three seat belts across the body and wrist and leg restraints are also available for combative or mental health patients.

"If there's any indication that you're a danger to yourself or others, that's what these additional levels are for," Bosten said.

But Bosten said the ultimate level of security is an EMT who is paying attention.

"If you go as fast as as you can (unbuckling three seat belts), it's still ... you've got to work to get to this point -- to open the door -- to get out of the vehicle. And that should be plenty of time for an attendant who is alert to start some sort of intervention," Bosten said.

Action Care Ambulance and Greenwood Village police are investigating the incident

The Sunday afternoon incident closed northbound I-25, near Orchard Road, for more than two hours.