An American Airlines flight made an emergency landing because of smoke in the cabin, and four people were treated at a hospital, authorities said.
The plane was en route from Dallas-Fort Worth to Newark, New Jersey, late Thursday, airport spokeswoman Rande Swann said. There were 123 passengers and five crew members on board, the airline said.
Two adults, including one crew member, and two children were treated in an emergency room, American Airlines spokesman Tim Wagner said.
The air conditioning system apparently malfunctioned, but there was no sign of fire as emergency personnel converged on the plane after it landed in Louisville, Swann told the AP.
"A few people were complaining of irritation and smoke inhalation," she said.
Passengers were provided hotel accommodations while another plane was brought in to take them to Newark on Friday, the airline said.