A blast shook the Russian town of Sergiev Posad on Wednesday, injuring at least 45 people, according to local authorities.
The explosion occurred at a factory 50 kilometers northeast of Moscow that produces optical equipment for industry and healthcare, as well as for Russian security forces.
The Russian state news agency TASS reported that the explosion happened in a warehouse containing pyrotechnic equipment.
According to TASS, local emergency services do not believe the incident was the result of a Ukrainian attack.
Moscow has been hit in recent months with a number of drone attacks, which Russia has blamed on Ukraine.