Two teens attempting to illegally cross the U.S. Border were severely injured last week after attempting to scale the wall, falling 18 feet.

Border agents said that at approximately 1 p.m. Friday, six aliens from Guatemala illegally entered the U.S. by climbing over the border wall just east of the San Luis Port of Entry.

A 14-year-old traveling with her mother fell 18 feet and sustained a serious back injury, officials said. Another teen, an unaccompanied 17-year-old girl, also fell and suffered an ankle injury.

Yuma Station Border Patrol agents and emergency personal arrived on the scene. The 14-year-old was taken to a local medical center where she was then airlifted to a Phoenix hospital. The other teen was stabilized on the scene.

“The only legal and safe method of entry into the United States is through a designated Port of Entry,” said Yuma Sector Acting Chief Patrol Agent Carl Landrum. “People entering our country illegally, at places other than designated Ports of Entry, put themselves and their families in dangerous situations that could result in significant injury or even death.”

Signs are located in multiple locations along the wall where the pair fell, warning about the dangers of scaling the structure.

The four illegal immigrants with the injured teens were taken into custody.