U.S. security agents searching a checked suitcase after an alarm went off at New York's LaGuardia Airport expected to discover weapons but instead found a stowaway Chihuahua, authorities said on Friday.

Staring back at the agents was a 7-year-old beige-and-brown dog that had sneaked into the luggage, which its owner had checked onto her American Airlines flight to Los Angeles, said Lisa Farbstein, spokeswoman for the Transportation Security Administration.

"She was just as surprised as we were," Farbstein said. "The woman said that the dog must have climbed into the suitcase and curled up in the clothing while she was packing for her trip."

The discovery on March 3 was made as the luggage was headed for the plane's cargo hold through the usual screening equipment. When an alarm sounded, agents popped open the suitcase to inspect its contents.

"The officer was very surprised to see the dog," said Farbstein.

TSA agents, whose past checked luggage searches have turned up such dangerous items as a gas-filled chain saw, reunited the tiny dog with its owner, who was not identified.

The woman contacted her husband, who retrieved the pet and brought it home.