A series of explosions at a southern Kazakh ammunition depot Monday led authorities to evacuate a nearby town of 40,000 people and saw dozens reportedly hospitalized.

The blasts near the town of Arys were caused by "a fire, which led to the explosion of some of the ammunition (at the depot)," Kazakhstan's defense ministry said in a statement. Footage captured from the area showed people fleeing with huge plumes of smoke rising towards the sky in the backdrop.

Health authorities said 46 people, including five children, were injured by explosions. Radio Free Europe's Kazakh service reported over 50 hospitalized, citing sources at two hospitals in the south of the country. Three people in a hospital in Shymkent, a city of one million, were in a serious condition, RFE reported.

President Kassym-Jomart Tokayev ordered the defense and interior ministers, as well as the head of the Turkestan region, to "urgently take measures to eliminate the effects of the munition explosions."

"It is necessary to ensure the residents' safety and identify the cause of the explosions," Tokayev said in a statement.

Defense Minister Nurlan Yermekbayev flew out to the area to personally oversee the emergency effort, state media reported.

The head of the administrative region where Arys is located said that the town would be evacuated "completely" on Monday.

"Given the scale of what is happening, we see that we need to evacuate the city as a whole," Umirzak Shukeyev, Turkestan regional head, said in comments published by the private Tengrinews website.

The government has introduced a state of emergency and begun evacuating Arys' 45,000 residents. About 1,000 police and army troops have been sent to the area to maintain order.

Residents of the town of Arys were bussed 50 kilometers away from the area, state media reported. An orange plume of fire and smoke was photographed billowing out from the depot.

Authorities also halted railway traffic in the area.

The explosions at the depot have been powerful enough to have been registered by the nation's seismic service.

The cause of the fire wasn't immediately clear. A criminal probe has been launched.