According to the press agency DPA, two people have been wounded by a blast at the Teutschenthal facility, located near the town of Halle, Saxony-Anhalt. At the same time, over 30 are believed to be blocked inside a safety area underground at a depth of about 700 metres.
MDR, meanwhile, has reported that 38 people are trapped at the site.
The authorities are currently measuring the hydrogen concentration because hydrogen deflagration could have caused the incident. There is no information about any toxic substances having leaked into the environment.
According to reports, the facility had been in use for over 80 years before its closure in 1982.