An experienced climber died Sunday when she fell about 30 feet off a climbing wall at a Grapevine, Texas, climbing gym. Police say the death was an unfortunate accident.

According to this story from WFAA in Dallas/Fort Worth, police say "52-year old Susan Mallioux likely forgot to clip herself into the safety rope system provided by [Summit Climbing]."

She was climbing with her boyfriend and his son. Once Mailloux reached the top of the wall, about 25 to 30 feet up, police say Mailloux let go, as if she thought she was tied in.

More from WFAA: "Once she got to the top of that road ladder she simply released as if she was attached to it and then she fell to the ground," said Sgt. Robert Eberling with the Grapevine Police Department.

The gym requires climbers to sign a waiver warning against all types of possible injury or death, including "freakish accidents which cannot be forseen." Police say Mailloux failed to clip into what's called an auto-belay, an automatic harness system that lowers a falling climber, slowly, to the ground.

According to another Summit climber, Ben Mann, who did not know Mailloux, "All of the rock walls are lined with ropes and about every five to ten feet there's a sign that says don't forget to clip in, or make sure you're clipped in."

Summit climbing was closed Monday and will be closed again today out of respect for Mailloux and her family.