Insecticide has been sprayed over the city of Dallas, Texas, for the first time in 45 years, to combat a deadly outbreak of West Nile virus, which is borne by mosquitoes.
Ten people have died and at least 230 cases have been reported in the state.
Almost half of all cases of West Nile virus in the United States this year are in Texas.
Beechcraft Twin Air two-engine planes carried out the spraying on Thursday night.
The BBC reports the process might be repeated if officials think the first attempt did not kill enough mosquitoes.
The virus was first discovered in 1937 in Uganda. It is carried by birds and spread to humans by mosquitoes.
Symptoms can include high fever, loss of vision and paralysis In extreme cases. Milder manifestations can include headaches and skin rashes.