A flight en route from Los Angeles to Atlanta was diverted to Oklahoma for an emergency landing when a passenger attacked two flight attendants and threatened to bring down the plane, authorities said.

In a statement, Delta thanked passengers and crew members who "assisted in detaining an unruly passenger” Friday night. It added that "the aircraft landed without incident and the passenger was removed by law enforcement”.

Delta Flight 1730 was well on its way from Los Angeles to Atlanta when a frightening commotion broke out in the front of the plane, according to the airline, witnesses and media reports.

As a man grappled with flight attendants — and shouted repeatedly that he was "going to take the plane down” — the pilot called over the public address system for "all able-bodied men” to come forward to assist.

Several, including an off-duty pilot, rushed forward. After a violent struggle partly captured on video, they were able to overpower the man. The plane then made an emergency landing in Oklahoma City, police said.

It felt "very surreal”, Benjamin Curlee, a young man who was seated in the rear of the plane, told CNN.

He quoted other passengers as saying the suspect was behaving in a "very weird way”, wearing elbow and knee pads and making inappropriate remarks.

"I am very thankful that it did not end badly,” he added.

Police in Oklahoma City took the suspect, identified as an off-duty Delta employee in his late 20s, into custody, reports said. His precise motive was unknown.

After complaining of chest pains and showing signs of what police said were mental issues, he was hospitalised.

No other injuries to passengers or crew were reported.

Police searched the plane before allowing the flight to continue on. The FBI is now leading an investigation, it told AFP.

The episode took place at a time when more Americans are taking to the airways than at any time since the pandemic broke out — and as "unruly passenger” events have surged sharply, often in disputes over mask-wearing.

Agents of the Transportation Security Administration on Friday screened more than two million passengers at airports — the most since before the COVID-19 crisis erupted, the agency said.

Meantime, data from the Federal Aviation Administration show that "unruly passenger” incidents have shot up this year amid high stress levels and as mask-wearing requirements have taken on a political edge.

The agency has launched 394 formal enforcement actions in "unruly passenger” cases through May 25 of this year, a far higher pace than the 183 for all of 2020, according to its website.

Many more cases have not led to formal action.