(CNN) -- Security concerns forced two U.S. passenger flights to be diverted Sunday, but both planes landed safely and eventually flew to their final destinations.
A Continental flight bound for Chicago from Houston made an unscheduled stop in St. Louis because of an "unruly passenger," a St. Louis airport spokesman said Sunday.
The man tried to reach the exit door during the flight but was stopped by a flight attendant, spokesman Jeff Lea said.
The plane landed at St. Louis and the man was taken off the plane for questioning by airport police and federal authorities, he said.
Continental Flight 546 finally landed in Chicago Sunday afternoon just an hour late.
A Delta flight was diverted Sunday after a flight attendant found a suspicious note in a lavatory, an official with the Transportation Security Administration told CNN.
The flight from Detroit headed to San Diego was diverted to Albuquerque, New Mexico, the FBI said, adding that it was informed of "a potential security threat" on the plane. Flight 1706 landed in Albuquerque shortly before 10 a.m. (12 p.m. ET) and agents were on the scene to investigate, the FBI office in Albuquerque said.
A spokesman for Albuquerque International Sunport Airport said passengers deplaned and were "being checked out."
TSA spokeswoman Kristin Lee said the flight landed without incident and that all passengers deplaned safely.
"Passengers and carry-ons were cleared by a canine team, and the plane was swept with negative findings," a TSA statement said.
CNN's Stephanie Gallman and Mike M. Ahlers contributed to this report.