HOUSTON -

A Southwest Airlines plane bound for Houston's Hobby airport was met by law enforcement officials Monday after a note about a bomb threat was discovered on board. 

Flight 24 was on it's way to Hobby airport from El Paso when passengers said a couple found the note. 

"It was a note that was found inside one of the magazines," said Martha Valdillez who was on board the flight.

Passengers said the couple who found it notified the flight attendants, who then made an announcement over the public address system.

"They said it was nothing to panic about," said Valdillez. "But, I mean, what can you do in these types of situations? It doesn't happen everyday."

People who were on board the flight said all of the 137 passengers did  remain calm, but that it was still scary.

"Yeah I was nervous," said Andres Garcia.  "I don't want to be on a plane when a bomb goes off in it."

Houston police had everyone get off the plane but leave their belongings behind. Bomb-sniffing dogs and investigators then went on board to check everything out and gave it the all clear about 30 minutes later. 

The couple who found the note was reportedly questioned by authorities. 

Officials have not said who may have put the note inside the magazine. Houston police are investigating.  

Southwest Airlines said the plane was cleared and immediately put back in service. 

This was the fifth incident in Texas in the past month involving airports and threats.

On Aug. 1, San Antonio's airport was evacuated after someone called and said three packages were left inside the parking garage.

A week later, bomb threats were made against three planes. One was flying into Houston's George Bush Intercontinental Airport and two others were headed to Dallas from Austin. All of those incidents turned out to be false alarms.

Investigators said they have not determined if any of the threats were connected.