Authorities are now saying that the propane tank in a box that caused a two-hour travel delay last week at the Minneapolis-St. Paul International Airport was empty.

The tank in a box aroused the suspicion of airline ticket counter staffers Friday morning, causing flight delays and the partial shutdown of Terminal 2.

Martha P. Morocho, 35, of Minneapolis, left the 2-by-2-foot box, which had tubes sticking out the top, on the floor of the ticketing lobby near the Travel Express store after the ticketing staff declined to check the box as baggage, police said.

Morocho then went through a security checkpoint and boarded her Southwest Airlines flight, said airport spokesman Patrick Hogan, who said he wouldn’t disclose the plane’s destination before the investigation was complete. She was soon removed from the plane.

Morocho was arrested and later released on her own recognizance, cited for leaving an unattended package, a misdemeanor.

Meantime, members of the Bloomington bomb squad deemed the tank not to be a threat.

A telephone message left at Morocho’s south Minneapolis home Tuesday seeking reaction to her arrest was not returned.

During the disruption, travelers were not allowed into the terminal to check in or to check their baggage, causing the flight delays. Travelers who already had cleared security and were in gate areas were allowed to remain there and board.

Airlines using Terminal 2 include Sun Country, Southwest, AirTran, Spirit and Icelandair.