Smoke rises from the site of blasts at an explosives plant in the town of Dzerzhinsk, Russia, on Saturday. Reuters

A blast at a major explosives plant in central Russia on Saturday injured at least 19 people and two were reported missing, officials said.

The explosion took place at the "Kristall" factory in Dzerzhinsk about 400 kilometres (250 miles) east of Moscow, in the Nizhny Novgorod region, a health ministry official told Interfax news agency.

"All of those who were injured -- around 19 people -- are receiving medical assistance," the official said.

"We are talking about shrapnel wounds of mild and moderate severity," she said.

The deputy governor of the Nizhny Novgorod region, Dmitry Krasnov, told Russian state television that "two people are missing."

Representatives of Kristall told Interfax that five people were working in the area where the explosion occurred and were safely evacuated.

There was no information yet on where the 19 injured were at the time of the blast.

Local fire fighters told agencies they had no information about any more people still inside the plant.

"There was a technical explosion in one of the workshops, followed by a fire of around 100 square meters," a spokesman of the local emergency ministry told news agencies.

Images on social media showed a large cloud of smoke after the explosion.

Agence France-Presse