US authorities have confirmed that the highly toxic pesticide methyl bromide caused a Delaware family to become seriously ill at a U.S. Virgin Islands resort, and that the chemical was used at the resort several times in the past year, officials said Tuesday. The US Environmental Protection Agency said it is contacting people including employees at Sirenusa resort in St. John to determine how many others might have been exposed to the pesticide. It was banned for indoor residential use in 1984. 'Methyl bromide is a potent neurotoxin, so it really affects your central nervous system,' EPA Regional Administrator Judith Enck said in a telephone interview. Steve Esmond and his wife, Dr Theresa Devine, and their two teenage sons fell seriously ill during their stay at the Sirenusa Condominium Resort on the island of St. John . The Esmond family had rented a second-floor condominium at Sirenusa, a resort of 22 villas, late last month. Steve Esmond and his wife, Dr Theresa Devine, and their two teenage sons fell seriously ill during their stay on the  island of St. John. The family were airlifted to separate hospitals in Philadelphia suffering major respiratory trauma. Sean, 16, and Ryan, 14, were  in critical condition. The family attorney James Maron confirmed the two parents are recovering but their two sons are in critical condition. James Maron, the family's lawyer, said the boys were in 'rough shape'. 'The family are all fighters,' he told WPBF News. 'They're fighting for everything right now. I understand it's a long recovery.' The US Justice Department has opened a criminal investigation. Sean, 16, (pictured) and his 14-year-old brother Ryan remain in comas two weeks after being hospitalized . Enck said the pesticide was used March 28 on the condominium's first floor, and agents are trying to determine how much was employed. She said the EPA found that methyl bromide was used at other Sirenusa units in the past year, but declined to say how many, citing the investigation. Sea Glass Vacations LLC, which rents units at Sirenusa, said in a statement it has terminated its contract with Terminix and the townhome under investigation is unoccupied. 'We are sending our thoughts and prayers to the family impacted by this tragic incident,' the company said. 'We remain committed to full cooperation with all local and federal authorities.' Terminix spokesman Pete Tosches said in a statement that the company is conducting its own investigation and is cooperating with authorities. 'We're committed to performing all work we undertake in a way that is safe for our employees, customers and the public,' he said. The family was staying at the $875-a-night  Sirenusa Condominium Resort on St. John in the US Virgin Islands . Enck said the EPA is awaiting results of air and wipe samples taken from the condominium. Maron said Esmond, who is an administrator of the private Tatnall School in Wilmington, is conscious but unable to move. Devine, a dentist, was treated and released from the hospital and is currently in occupational therapy. The Tatnall school, where Sean was a star lacrosse player, posted on their Facebook page that they had the Middle School students write get wall cards for Esmond and his family. 'The entire Tatnall community continues to direct its supportive energy toward the Esmonds and asks that everyone keep the family in their thoughts and prayers during this difficult time.' On Friday  the US Environmental Protection agency said preliminary tests showed there was 'a presence of methyl bromide in the unit where the family was staying' Tuition at the Tatnall school can range from $20,000 to $25,000 a year. Methyl Bromide, which is odorless, can be fatal or cause serious damage to the central nervous system and respiratory system, according to the EPA. It is acutely toxic, and only permitted to be used outdoors by certified professionals in the US. Sea Glass Vacations, which acts as a rental agent for several units at Sirenusa Condominium Resort, said the unit where the family was staying was not treated with a pesticide, but rather the unit immediately below their suite. Maron said when paramedics arrived at the villa Esmond was found unconscious.
Steve Esmond, his wife Theresa Divine and their two teenage sons fell seriously ill while staying  at the Sirenusa Resort in St. John . Divine was released from hospital and is now in occupational therapy . The family's lawyer said the boys are in 'rough shape' On Friday the US Environmental Protection Agency said preliminary tests showed there was 'a presence of methyl bromide in the unit .