The death toll from last week’s explosion and fire at an industrial plant in Russia’s Ryazan region has climbed to 24, with at least 157 others injured, officials said Monday.

The blaze broke out Friday at the Elastik plant in the Shilovsky district, about 155 miles southeast of Moscow. Russia’s Emergency Situations Ministry said search and rescue teams were still working through the debris.

According to state news agency RIA Novosti, a gunpowder workshop at the facility caught fire, sparking a powerful explosion that destroyed parts of the building. Images released by the emergency ministry showed a factory hall reduced to rubble.

Local authorities declared Monday a day of mourning across Ryazan.

Investigators have opened a criminal case into alleged violations of industrial safety rules, suggesting the blast was not the result of a Ukrainian attack. Russia’s 112 Telegram channel, which is closely linked to law enforcement, reported that the explosion may have been caused by a rogue shell detonation. It also noted the factory had previously received multiple warnings over labor safety violations.

Fatal accidents are not unusual at Russian factories, where poor oversight and mismanagement have led to repeated disasters. In 2021, another blast at the same plant killed 17 people, and several managers were later sentenced to prison.

Since Russia’s invasion of Ukraine in 2022, Kyiv has targeted Russian industry and infrastructure with sabotage attacks, raising questions after such incidents. But investigators say this latest tragedy points instead to chronic safety failures inside the plant.