MELBOURNE, Australia -- One of Australia's main airport terminals was shut down for eight hours as emergency crews hunted in vain for the cause of a mystery illness which struck down nearly 60 staff and passengers in the building, officials said.
Paramedics, firefighters and hazardous materials crews in full protective clothing rushed to Melbourne airport early Monday after staff in a domestic terminal began suffering nausea and vomiting, dizziness, headaches and shortness of breath.
Up to 2,000 staff, passengers and their friends were evacuated and the terminal shut down around 10:00 am while emergency crews tested air conditioning units and other facilities in an unsuccessful search for what was causing the illness.
Ambulance service spokesman James Howe said 47 people were taken to hospital and another 10 were treated at the scene for the symptoms.
Most of those hospitalised were released later in the day.
"They were certainly quite distressed ... so whatever substance this has been has certainly caused a physiological response," said another ambulance service official, operations manager Paul Holman.
Those affected were mostly security and airline staff working in the departure area for domestic carrier Virgin Blue, officials said.
The shutdown of the terminal caused chaos around the airport, forcing the cancellation or postponement of scores of Virgin Blue and other domestic flights.
In all, airline officials said, up to 20,000 people -- passengers and those dropping or picking up travellers -- were affected by the prolonged closure.
A Virgin Blue spokeswoman said the terminal reopened at 6:00 pm and flights resumed about two hours later.
"We're trying to move as many people as we can tonight," Amanda Bolger said.
While some kind of toxic gas was the main suspect in the incident, the exact cause of the contamination remained a mystery.
"The source has not been located or identified," a Melbourne fire brigade spokesman said Monday night. "All (chemical detection) readings are showing zero."
He said firefighters had spent the day testing everything they could, but found nothing. "Unfortunately, whatever it was has now dissipated," he said.
Terminals servicing international air traffic and the Australian flag carrier Qantas continued functioning normally throughout the day.
