A man was arrested in Vallejo Thursday after police allegedly found a loaded gun that police say he tried to bring to a high school graduation ceremony.

The Vallejo Police Department was conducting extra patrols at the Vallejo High School graduation Thursday when officers noticed a man “displaying behaviors consistent with carrying a concealed firearm,” police said in a social media post.

Officers apparently observed a weighted, “L-shaped” bulge underneath his clothing. They also noticed the man repeatedly adjusting the object, holding it against his body while walking, and checking it with his hand, according to the department.

As the man got near the entrance to the graduation ceremony, police said that officers observed him “become hesitant” after he noticed the security screening area and metal detectors.

The man then walked back toward his car nearby, where officers saw him place items inside the car before returning to the ceremony.

Officers continued their investigation after the ceremony and detained the man. They allegedly found a loaded firearm equipped with an extended magazine in a backpack located in the car where he had stored his belongings.

The gun was unregistered and police discovered that the man, an Antioch resident, was not legally allowed to possess the handgun due to his age.

The suspect was arrested and booked into jail.

“This case highlights the importance of proactive policing, officer vigilance, and coordinated teamwork during large community events,” the department said in a statement.

Alise is a general assignment reporter with a focus on covering government, elections, housing, crime, courts and entertainment in San Francisco and on the Peninsula. Alise is a Bay Area native from San Carlos. She studied history at University of California, Santa Cruz and first started journalism at Skyline College’s school newspaper in San Bruno. She has interned for Bay City News and for Eesti Rahvusringhääling, or Estonian Public Broadcasting. She has covered everything from the removal of former San Mateo County Sheriff Christina Corpus to the divisive battle over the Great Highway on San Francisco’s west side. Please send her any tips.