Hundreds of people have been evacuated from the airport in Melbourne, Australia, after mysterious fumes spread through the airport terminal early Monday morning.

A spokesperson for the Metropolitan Ambulance Service said 21 people have been hospitalized with symptoms that include vomiting, nausea and breathing difficulties.

The terminal, which handles domestic flights by Virgin Blue, was evacuated and numerous flights were canceled.

The source of the fumes was not immediately known.

Most of those affected were security or airline personnel.

Some information provided by AFP and AP.