MOSCOW (AP) — At least 17 people have died in last week’s fire at a Russian military research facility, authorities said Monday.

The regional government in Tver, a city about 180 kilometers (112 miles) northwest of Moscow, said that so far only five of the victims had been identified.

The blaze at the Central Research Institute for Air and Space Defense of the Russian Defense Ministry in Tver erupted Thursday and it took authorities a day to put it out.

Officials previously said 27 people were injured and 13 of them were hospitalized.

The cause of the fire wasn’t immediately clear.

The research institute was involved in the development of some of the state-of-the-art Russian weapons systems, reportedly including the Iskander missile.