A United Airlines Boeing 757-200 jet lost one of its main landing-gear wheels shortly after taking off from Los Angeles International Airport.

There are four wheels each on the plane’s two landing gears and another two on the nose gear.

According to the Federal Aviation Administration, the plane landed safely at Denver International Airport at around 10:10 a.m. local time on Monday.

An Allegiant Airlines pilot waiting to take off witnessed the incident and informed air traffic control.

“A tire came off that B757 that took off. We saw it rolling down … its tire came off and came rolling past us,” the pilot said, according to audio from LiveATC.net.

There were no injuries on the ground or aboard the plane, which was carrying 174 passengers and seven crew members.

“The wheel has been recovered in Los Angeles, and we are investigating what caused this event,” United Airlines told the Associated Press.

The plane used Monday was first delivered in 1994, a Boeing spokesperson told the Agence France-Presse wire service. Manufacturing of the 757-200 model was discontinued in 2004,

In March, a landing-gear tire from a United Boeing 777 fell off during take-off at San Francisco International Airport and landed on cars in a parking lot below.

That plane had to make an emergency landing in Los Angeles before heading on to its ultimate destination in Japan.