First Lady Melania Trump's plane returned to Joint Base Andrews Wednesday morning after people on board saw smoke and smelled burning.

Trump's spokesperson, Stephanie Grisham, confirmed to USA TODAY there was a "minor mechanical issue" on the plane. She added: "Everything is fine and everyone is safe."

Trump later boarded a different plane to an event in Philadelphia that is expected to continue as scheduled.

Several journalists on Trump's flight reported a "thin haze of smoke" and the smell of something burning about 10 minutes after takeoff from Joint Base Andrews in Maryland. People on board were given wet towels to breathe through if the smell became too strong.

The plane safely landed back at the air base shortly after, a press pool report said. One crew member told a journalist that a "malfunctioning comms unit' had overheated.

Trump is visiting Philadelphia to meet with families of children who were affected by exposure to opioids while in the womb.

Trump is expected to be joined on her visit to Thomas Jefferson University Hospital by U.S. Health and Human Services Secretary Alex Azar. The hospital has provided care to mothers with opioid use disorder and their newborn children for more than 45 years.

Mrs. Trump also planned to tour a neonatal intensive care nursery and speak at a U.S. health department conference on a new system that tracks infants suffering from opiate withdrawal.

The first lady's visit is one of the stops she's making to promote her "Be Best" campaign, which focuses on major issues affecting children, including the importance of healthy pregnancies.

Contributing: Associated Press, USA Today