( CNN ) -- The rats die hard in Iran . Sharpshooters in Tehran are training their air gun scopes on the country 's longstanding rodent problem . Rats are reportedly running rampant in 26 districts in the capital . Iran has the biggest beef with Norwegian rats , Mohammad Hadi Heydarzadeh , a top environmental official , told CNN . He said the critters have `` entered Iran from abroad by cargo ships . '' Though it 's unclear if the rats come with paperwork , a search of ratbehavior.org shows that that particular kind of rat can grow 16 inches long . And they are very aggressive , `` fighting , chasing , biting and boxing . '' While the Iranians have used poison to kill the rats during the daytime , at night the teams of sharpshooters use infrared lenses to hunt them down . `` We have identified the rats ' places of congregation by using ( computer ) software , '' Heydarzadeh explained . By the end of 2013 , the Iranians hope to have 40 teams of shooters working , he added . So far , 2,205 rats have been killed . Their bodies are carted off and incinerated or buried in special dumps , the environmental official explained . University researchers are working with the government to assess whether their newest plan of attack is working . But Heydarzadeh feels good . `` The number of these rodents in Tehran , '' he said , `` is on the decline . ''
Big rats are reportedly running rampant in 26 districts in Tehran . The government uses poison , and teams of sharpshooters are killing the rodents with air guns . The biggest headache is Norwegian rats , which can grow to 16 inches .