The incident occurred on Thursday in the hall of a garbage disposal operation in Hörsching, as the police said in the morning.
According to Austrian police, nine people have been injured, including three seriously.
"An explosion of a company building of #AVE in Hoersching. Several people injured!" the police tweeted.
The cause of the explosion was initially unclear. Three other people were reportedly slightly injured.
Thirteen fire brigades arrived at the scene of the incident.
A police spokesman said that there were no indications that an explosion at a waste disposal facility was caused by a terrorist attack.
Air traffic was not affected by the fire. According to Linz Airport, the wind is blowing in a favourable direction, driving the smoke column away from the apron of the airport.
Linz Airport does not expect that flights will be canceled.