"They said we must go home because the building was on fire," said a staffer on Monday, who asked not to be named.
However, spokesperson William Baloyi told the Mail & Guardian it had now been established that one of the air-conditioning units had overheated and released gas into the air.
"They evacuated us and we have now been told there is no longer any danger," Baloyi said.
"All the arms procurement commission documents are safe and the security of the commission is intact. Just to play it safe that there is no more gas around, I will not call people back to work today."
The commission took a great deal of heat after senior researcher Mokgale Moabi resigned in January, claiming that its chairperson Judge Willie Seriti had a second agenda and was running a covert operation.
Law researcher Kate Painting also walked off the job in March, after telling her colleagues she was quitting the post to retain her integrity.
However, Baloyi has claimed the commission is still on track and a new line-up of witnesses for the August hearings will be announced shortly.
Unhappiness
The M&G has been informed by several sources close to events that one of the two commissioners, Judge Francis Legodi, has expressed unhappiness at the way the commission is running.
Last month, Legodi heard billionaire entrepreneur Mark Shuttleworth's complex bid to have South Africa's exchange control system declared unconstitutional in the North Gauteng High Court, and reserved judgment in the case.
Baloyi said Legodi had not resigned from the commission.
Legodi would never compromise the commission, which takes precedence to his assistance at court, he said.
"Commissioner Legodi is not on the roll of the high court, but helps when the need arises and when available to do so," said Baloyi.
"It is worth mentioning that to date Judge Legodi continues to participate in all dealings of the commission, and there is no need to speculate on whether or not he will be presiding over the public hearings of the commission, scheduled to start in August."