One passenger on United Flight 836 was treated at a hospital, United spokeswoman Megan McCarthy said, but she did not know which hospital or the passenger's condition.

The plane's 258 passengers and 15 crew members were evacuated and bused to a terminal, according to Gregg Cunningham, a spokesman for Chicago's Department of Aviation.

One of the Boeing 777's four pilots reported smoke in the cabin around 3:45 p.m. CST. The plane landed minutes later and was evacuated as a precaution, McCarthy said.

Officials did not know the cause of the smoke.

In Columbus, Ohio, meanwhile, a tire on a Delta Air Lines flight exploded shortly after takeoff Friday night, forcing the pilot to make an emergency landing, an airline spokeswoman said. There were no reports of injuries to the 140 passengers.

The MD-88 jet took off from Port Columbus International Airport about 5:15 p.m. for Atlanta, Delta spokeswoman Ashley Black said. The plane circled the Columbus area for about 90 minutes to burn fuel before landing.

It was unclear which of the jet's tires exploded.