Oceanside police report that Jefferson Middle School was locked down at about 11 a.m. Monday.
The incident began at a little before 11 a.m. after someone reported seeing a female student pull a gun out of a backpack in a girls' bathroom, officials said, adding that the backpack was located. There was no gun inside, however, according to authorities.
Police said later that the student who first reported the gun told investigators that she overheard two other female students talking about a gun in the restroom and did not actually see the weapon.
To be safe, however, police decided to go through every room and outbuilding on campus to see if a weapon was stashed anywhere at the school.
A thorough search of the middle school proved negative, and no handgun was found, according to police.
Jefferson Middle School, which is located at North Canyon Drive and Mission Avenue in Oceanside, was the only campus affected.