Up to 600 people have been evacuated from a university library in Melbourne's CBD amidst fears of a major gas leak.
A Metropolitan Fire Brigade spokesman says the suspected leak at RMIT University on Saturday had stemmed from hazardous waste which had been stored incorrectly.
"Therefore, the off-gassing from this waste had permeated the air-handling system, alarming the students and staff," he said in a statement.
"The scene and students are safe."
The waste will be dealt with by Environment Protection Authority officers.
Traffic in the area was disrupted as staff and students were evacuated.
No one has been injured.