A fire followed the blast which happened around 08:45 (07:45 GMT) at the Baumgarten site, just east of the capital Vienna, near the Slovak border.
Lower Austria police issued a brief statement on Twitter, saying the situation was under control. He added that "technical problems" caused the explosion, and that there was "no indication of terrorism." .
Squads are now searching for people in the rubble, and locals have been warned to stay away from the area.
A spokesman for the fire brigade said a number of cars in the vehicle park had melted due to the heat and six buildings were on fire. Gas Connect Austria says that after the explosion, "transit through Austria to the south and southeast is impaired until further notice". The facility was "shut down in a controlled state and is offline", the company said.
Italy will declare a state of emergency after an explosion at a gas plant in Austria cut off supplies from Russian Federation, the Italian energy minister said on Tuesday.
Wholesale gas prices in Britain rose to their highest level since 2013 yesterday as a "perfect storm" of cold weather, the closure of the Forties pipeline in the North Sea and an explosion at a gas plant in Austria hit European markets. "As a result of the event in Austria. we adjusted the transit regime in our network to fully secure its safety and suspended transit to Baumgarten", a spokesman for Slovakian gas operator Eustream said, as quoted by Reuters.
Operator Gas Connect Austria assures that the national natural gas supply can be recovered for the foreseeable future. It handles some 40 billion cubic meters from Russia, Norway, and other countries per year, Deutsche Welle reported.