American Family Poisoned in their Luxury Hotel on Spring Break

An odorless and colorless poison is to blame.

We're learning more about the nightmare spring break for this American family. They were poisoned inside their luxury villa in the U.S. Virgin Islands.

It happened to the Esmond family in the second floor suite at the beautiful Sirenusa Resort. Dad Steve Esmond was found unconscious. His wife, Theresa, and their two sons were also overcome.

The tragedy took place after the unit directly below them was fumigated with the chemical Methyl Bromide, an odorless and colorless pesticide that's used in farming but has been banned from use indoors for three decades.  

Watch: Poisoned Ice Tea nightmare.

Terminix, which was hired to fumigate the apartment, said in a statement: "We're cooperating with authorities in their investigation, and we're conducting our own thorough internal investigation."

The Esmonds, who live in Delaware, were airlifted back to the U.S. Dad is said to be alert but unable to move. His 16-year-old son Sean, a star high school lacrosse player and his 14-year-old brother, Ryan have not regained consciousness at Children's Hospital of Philadelphia. The family lawyer said "The boys are in rough shape."

Internist and lung specialist Dr. Len Horovitz told INSIDE EDITION, "The long lasting effects could be blindness, hearing problems, motor problems like the inability to walk. Complete recovery from something like this could take months to years."

Read: Mom Convicted of Poisoning Son With Salt, 'Seemed to Relish Attention.'

Mom, Theresa, who is a dentist, has been released. The boys attend the exclusive Tatnall School in Delaware, where their dad is an administrator.

"If this poor family hadn't been discovered when they were they call could have died," said Dr. Horovitz.