Airport officials or the Federal Aviation Administration could not be immediately accessed for emergency comments.
But a passenger aboard United Airlines aircraft, John Murray, gave CNN an obvious explanation: His aircraft was diverted to Newark due to an emergency with the plane shortly after taking off from New York's LaGuardia airport at Saturday morning.
"All I know is that 10 minutes after takeoff we didn't get much height, we just turned around northern New Jersey and didn't go anywhere," he said. "It was when we landed … at Newark."
"Emergency herds led us out of the plane" after landing, he said.
"I spoke to one of the emergency servants who told us that we apparently had a flat tire and there was something about friction … and it was possibly smoke, and so we had to do the emergency landing."
Airport announced the emergency around 8:35 ET
The airport originally forced around 8:35 ET ET that no arrivals or departures were allowed due to an emergency.
All passengers were eventually taken to a terminal, Murray said.
His aircraft, United Airlines Flight 2098, had been tied to Houston's George Bush Intercontinental Airport .
United could not be reached immediately for comment.