Many eyes looked skyward Tuesday afternoon when a loud, frightening noise rumbled over Berkeley.
"When I heard it I thought someone was invading Berkeley or something," UC Berkeley student Liam Rohlsson said. "Our whole building shook. It was kind of crazy."
Turns out, it was a US Navy fighter jet on a training mission returning to its air station in the Central Valley.
An online flight tracker traced the jet's path coming in from the Golden Gate Bridge and over the Berkeley Hills, never going below 2,500 feet then down to its base. Some people thought the jet was flying much lower than that and feared it would hit buildings.
"We're used to helicopters all the time, but this was clearly really loud, really booming," said Michele Hammond, who works on the Cal Berkeley campus.
When online news site Berkeleyside posted a story on the jet flying through town, someone going by the name "TheCulprit" wrote in the comment section that he was a Cal student and his brother was the pilot of the jet essentially saying "hi" to him.
"The Navy would not confirm the identity of the pilot, but we fell confident that based on our interactions with him, he's telling us the truth," said Emilie Raguso, a senior reporter at Berkeleyside.
In a statement, the Naval Air Forces said: "While training missions in the local area are common and the pilot was under positive FAA control, the US Navy is investigating the flight to ensure the aviator complied with all FAA and US Navy regulations."
If the flight was, in fact, just a shout-out to the pilot's brother, some people thought it was cool, while others are upset.
"A lot of people were scared by it. They don't know what it was," resident Jeremiah Holland said. "It's completely inappropriate to be using public resources to be doing something like that when the danger could be so great."