The FBI is investigating whether online threats against three airline flights caused an Orlando-bound flight from Los Angeles to be diverted to Dallas Sunday.
The flight was diverted to Dallas Sunday afternoon due to "a security concern," a Delta Air Lines spokesman said.
The flight eventually landed at Orlando International Airport around 10:30 p.m.
The FBI is also investigating threats against flights to Seattle-Tacoma International Airport where the planes had to be evacuated.
FBI spokeswoman Laura Eimiller said Monday that agents were investigating whether the threats came from the same person or from copycats.
Law enforcement determined the public was not at risk.
Such threats are not rare. Eimiller said federal officials take them seriously and suspects can be prosecuted.
The evacuations come a day after bomb threats targeted two jets bound for Atlanta, prompting F-16 fighter jets to escort the planes. Saturday's threats targeted Southwest Airlines Flight 2492, which arrived at Atlanta from Milwaukee; and Delta Air Lines Flight 1156, which arrived from Portland, Oregon.
It was unclear if any of threats were connected.