© Derik Holtmann/BNDExterior of the post office at Scott Air Force Base.
Three people were taken to the hospital and another 14 were decontaminated after workers in the Scott Air Force Base post office suffered nearly simultaneous skin and respiratory reactions at 9:30 a.m. Wednesday.

After what was termed an exhaustive investigation, investigators were not able to determine what caused the workers to become ill, Scott Air Force Base spokeswoman Karen Pettit said Wednesday night.

Investigators found nothing suspicious and no trace of a chemical or an odor, Pettit said. Whatever caused the workers' illnesses may have dissipated enough that it wasn't detected, she said.

"They couldn't determine it came from one specific package," Pettit said.

Earlier Wednesday, Col. Michael Hornitschek had said investigators isolated the source to a particular bin of mail which they were going through methodically.

FBI agents were investigating. Postal inspectors were also on site to offer help to Air Force personnel, said Valerie Hughes, spokesman for the U.S. Postal Service. Their investigation was closed Wednesday night after it was determined it was not a suspicious incident, Pettit said.

Hornitschek, 375th Air Mobility Wing commander, said he believes this is an isolated incident and has no reason whatsoever to believe that this is related to the upcoming 9/11 anniversary.

"We don't want to jump to any conclusions. It could be anything in the mail center, it could be the package. It could be a benign shipment someone sent that leaked or broke," Hornitschek said. "It might not be coming from the package itself."

All areas of the base that were closed Wednesday, except for the post office's mail center, were to be reopened today, including the areas of the post office where the clerks are stationed and where customers receive and send mail. The mail center -- its distribution and processing area -- was to remain closed another day for further monitoring and its functions moved to an alternative site.

The mail was delivered on base on Wednesday with a two-hour delay.

Building 1650, the base's mail center, was evacuated and three people were taken to Memorial Hospital in Belleville for treatment of skin reactions and respiratory difficulty due to possible chemical exposure, base spokesman Capt. Kathleen Ferrero said. All three reported smelling a chemical shortly before experiencing the reactions.

The other 14 people -- 13 service members and one civilian -- were decontaminated at the base as a precaution and evaluated by medical personnel, according to a base press statement. The decontamination process involves stripping down and being hosed down.

Tents were set up in the parking lot in front of the postal center but the decontamination process was later moved to the base clinic. None suffered from the same illness suffered by the three mail center workers.

Of the three people treated for exposure, two were U.S. Postal Service employees and one was a U.S. Air Force service member. The three suffered an itching sensation to their skin and respiratory problems. None of the three sent to the hospital had any lingering effects, Hornitschek said.

Thirteen of the decontaminated people were in the mail center at the time of the exposure, the 14th person responded to a base-wide announcement over the loud speaker system indicating anyone experiencing suspicious health issues should immediately report to the base clinic. The person who reported to the clinic was treated and released.

The three people taken to Memorial were treated and released by noon Wednesday, Ferrero said.

"The three released from Memorial Hospital are doing fine now," Hornitschek said. "They are now talking to investigators about what happened and what they experienced as part of our investigation."

Hornitschek said hazardous material specialists at the base are investigating to find out what the substance that caused the skin and respiratory reactions was. Workers in red hazardous materials suits were outside the post office about 3 p.m. Wednesday.

The base's education center, bowling alley, Information Tickets and Tours office and Airman Family Readiness Center were all closed until further notice.

"We are working diligently to resolve this," Hornitschek said. "We are in the recovery phase now and investigating this to find out what it is."

Businesses and buildings around the post office were evacuated of about 100 people. The post office is located on the west side of the base by the bowling alley, theater, Shoppette, Burger King and Pronto's Pizza, just east of the MetroLink station.

"Fortunately this is not a common occurrence at Scott Air Force Base but we do have protocol in place to protect our people here on base and in surrounding communities if necessary," Hornitschek said.

All packages coming in to the base are rigorously screened, Hornitschek said. The suspected package remained isolated inside the mail center while hazardous material experts prepared to test it for chemicals and explosives.

"They are experts in this kind of thing and will continue to test it until they find out what it is or can give us an all-clear," Hornitschek said.

Emergency personnel from Scott Air Force Base, Belleville and O'Fallon responded. Hornitschek said the FBI has been contacted in reference to the incident as part of the base's contingency protocol procedures during a possible hazardous materials leak.

Four firefighters responding to the emergency were affected by the heat, but none seriously. They were taken to sit down, cool off and drink water until they felt better, Hornitschek said.

"I am confident there is no threat to the base personnel or to surrounding communities," Hornitschek said. "There is no threat to the base, it's business and life as usual. If we felt there was a threat, we would certainly let people know."

Ward Drive and West Birchard Street were closed in front of the Shoppette and the mail center.

The base employs about 14,000 people daily. Military retirees and others were asked to reschedule visits to the base.

Last week, Hornitschek said the base was tested on its hazardous materials response procedures and rated excellent.