MOSCOW >> Six people died and 27 more sustained injuries after a fire broke at a defense research facility in the northwestern Russian city of Tver on Thursday, authorities of the Tver regions said.

The fire erupted in an administrative building of the Aerospace Defense Forces’ Central Research Institute, which operates under the Russian Defense Ministry. It quickly engulfed the building’s upper three floors, forcing those inside to jump from windows and causing the roof to cave in.

Regional military prosecutors are investigating the cause of the blaze. The state-run news agency Tass said early findings pointed to aging wiring as a contributing factor.

According to the website of the Russian Defense Ministry, the institute focuses on research related to air and space defense, including the development of new anti-aircraft systems.