Updated

As Tehran's rodents become increasingly resistant to poison, Iran has a new way to combat the growing pest population: snipers.

Ten sniper teams reportedly have been deployed to combat the capital city's growing rat population, which currently outnumbers Tehran's 12 million human residents, according to The National.

"It's become a 24/7 war," said Mohammad Hadi Heydarzadeh, the head of Tehran municipality's environmental agency. "We use chemical poison during the day and the snipers at night."

The sharpshooters have bagged more than 2,000 rats in recent weeks, The National reports, but the surviving pests appear to be mutating.

"They seem to have a genetic mutation," said Ismail Kahram, an environmental adviser to the city council. "They are bigger now and look different. These are changes that normally take millions of years of evolution."

Kahram says the rats are so big, they even outweigh many of Tehran's cats.

Officials say the city is now working to boost the number of sniper squads to 40, according to The National.

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