They made her put out her cigarette. She then threatened to kill everyone on the plane.

During a Dec. 2017 flight, a woman was asked to put out her cigarette. She responded by threatening to kill everyone on the plane. (Courtesy of the Washington Post)

Southwest Airlines says it all started with a cigarette.

A passenger was smoking in the bathroom somewhere between Portland and Sacramento on Saturday, according to the airline, and had gone so far as to tamper with the smoke detector.

So a flight attendant barged in on the woman, according to KOIN 6. This at least got her out of the bathroom, but did little else to improve the situation on Flight 2943.

The woman ripped an oxygen mask out of the ceiling as crew forced her back to her seat, the station reported. And indeed, a mask appears to dangle in the plane aisle as seen in video of the ensuing tirade.

"I have a destination for myself!" the woman yells as a passenger behind her looks up from his tablet and stares. She is wearing a hat, sunglasses and overcoat, and collecting her belongings as if to disembark the mid-air flight.

"I swear, if you don't . . . land," the woman says, as a flight attendant blocks her from the aisle, "I will kill everybody on this f-ing plane!"

"You will not," the attendant says. "You will not."

"I will!"

A scuffle in the aisle ends the video. The man who took it told CBS 13 that the woman had to be restrained by passengers and crew for the next half hour.

Meanwhile, the airline said, pilots called in an emergency and landed in Sacramento, somehow more or less on schedule.

Sheriff's deputies were waiting at the airport. They arrested Valerie Curbelo, 24, on a felony charge of making a death threat and jailed her on $75,000 bail.

CBS 13 sent a reporter to the jail to get her side of the story. It didn't clarify matters much.

"Why did you decide to smoke in the bathroom?" the reporter asked Curbelo. "That's what they say you were doing."

"The anxiety," Curbelo said. "Yeah, the anxiety."

"You were saying some pretty threatening things," the reporter continued. "Like, you were going to kill everybody on the plane."

She nodded.

He asked why.

"I don't know," Curbelo said. "It was not me. It was not me."

Curbelo, who lives in Oregon, was still jailed Monday afternoon. It's unclear whether she has a lawyer.