UPDATE NOON: Investigations into a suspect package discovered at the Toowoomba mail centre this morning are continuing.
Darling Downs Detective Inspector Dave Isherwood said inquiries were continuing into what the item and its contents were after the parcel was reported to authorities about 8.40am.
"It's still in the infancy stage," he said of the investigation.
10AM: Scientific officers will test a package with a "significant amount" of white powder inside found at the Toowoomba mail centre this morning.
The package was found this morning in a sorting area at the Australia Post mail centre in Kearneys Spring. It was believed to have been delivered yesterday.
"It's a significant amount of white powder in a package and it has obviously caused concern with the oncoming shift today," QFES station officer Neil Goodman said.
"The issue wasn't addressed yesterday.
"We're here today to try and bring it to a successful conclusion."
The suspicious package is under police guard inside the centre from where a sample will be taken and tested for explosive and flammable properties.
That will be done outside the sorting centre away from workers who have been moved "to a safe distance" from the facility.
It is expected to take about an hour for specialist scientific officers to arrive on scene and perform the tests safely.
"We've isolated the area inside and it is currently under police guard," Mr Goodman said.
"Two fire officers in breathing apparatus will take the sample, package it inside and bring it to fresh air."
9AM: Police are investigating a number of suspicious packages at the Toowoomba mail centre after white powder substances were found this morning.
Specialist fire units are conducting air sampling tests after the packages were reported about 8.30am.
Police, QFES and QAS units are on scene at the Stenner St complex.
It's unknown how many packages were located, and investigations are continuing.