Two strangers were caught engaged in a sexual act on a Delta Air Lines flight from Los Angeles to Detroit Sunday night, airline officials said.

The 48-year-old woman and 28-year-old man, who have not been publicly named, reportedly had not met before the flight, during which the woman allegedly performed oral sex on the man while they were both in their seats, police told WDIV-Local 4 in Detroit. The man was flying to Detroit to catch a connecting flight to Miami, while the woman was going to catch a connecting flight to Nashville.

“The act within itself is very inappropriate in a public space,” a passenger on the flight told WDIV-Local 4.

“There are children,” she added. “There are families. There are seniors. These things should be respected.”

FBI officials told WDIV-Local 4 that the incident is still being investigated, and that the man and woman could be charged with a misdemeanor or felony. Both were issued citations. FBI officials said that the man and woman could be charged as early as Tuesday.

A Delta spokesman declined a request for comment by The Washington Post.