Ann Romney plane makes emergency landing in Denver

"All okay. Thank goodness," the spokeswoman, Andrea Saul, wrote on Twitter.

Saul added the cause of the emergency was apparently "an electrical fire" after the cabin of the plane filled with smoke. Romney's plane was headed to Los Angeles but landed in Denver, where it was met with emergency vehicles on the runway.

Ann Romney's press secretary, Sarah Haley, was also on the plane.

An official with the Federal Aviation Administration said no injuries were reported on the plane, which was on its way from Omaha, Nebraska.

"A Canadair Challenger 601 charter flight operated by World Wide Jet, diverted to Denver today at about 2:40 p.m. MDT after the pilot reported smoke in the cockpit. The flight was en route from Omaha, NE to Santa Monica, CA. The aircraft landed safely on runway 35L and passengers exited the aircraft via stairs on a taxiway. No injuries were reported," Laura J. Brown, deputy assistant administrator for public affairs with the FAA, said in a statement.

A Secret Service official confirmed the incident.

"We can confirm that a plane carrying Mrs. Romney and two Secret Service personnel did make an emergency landing about 4:25 ET. It was at the Denver airport," the official said. "Basically what we understand there was some type of smoke in the cabin. All personnel were safe."

The official could not say who else was on board.

Campaign spokesman Rick Gorka said Mitt Romney spoke with his wife on the phone and is set to take the stage at a campaign event in Las Vegas.

Unrelatedly, the emergency landing came days after Romney's campaign canceled an event in Colorado on Sunday due to investigations of a plane crash at the Pueblo airport. The campaign said they did not want to "interfere" with the investigation.