A shooting outside the offices of YouTube on Tuesday prompted an outpouring of support from fellow technology workers, as well as a sense of dread over whether other corporate headquarters in Silicon Valley were vulnerable to similar attacks.

YouTube’s campus in San Bruno, California, where three people were injured by gunfire, is laid out much like other tech offices nearby. It consists of a group of buildings within close proximity, spread across a suburban area. There’s outdoor seating and grassy pastures inviting colleagues to congregate. Locals and employees can wander freely together in the vicinity, and security guards typically stay at desks inside the buildings.

“Companies invest in security but purposefully keep physical security measures discreet because the vibe is casual and relaxed,” said Joe Sullivan, the former chief security officer at Uber Technologies Inc. and Facebook Inc. who’s now an independent consultant. “Leaders want to stay connected with their teams, generally choosing less visible security than you would see in traditional finance or media companies.”

A woman — identified by police as Nasim Aghdam — shot and injured at least three people before killing herself. She was found at the scene and appeared to be dead of “a self-inflicted” gunshot wound, San Bruno Police Chief Ed Barberini said at a press conference Tuesday. No motive was given for the shooting.

In an American age where shooting rampages have become increasingly common, openness can work against companies, said Jeff Harp, a retired agent at the U.S. Federal Bureau of Investigation in San Francisco who consults for technology companies. While employees are required to badge into buildings, access to many outdoor areas is generally accessible to all.

The episode could prompt executives to tighten security, Harp said. “Companies are going to be asking themselves, ‘Maybe our guard services need to be where they pull into the parking lot.’”

The modern tech office park is modeled after a college campus. At Google and Facebook, employees walk or ride bikes between meetings. Executives take pride in showing off their architecture to the public. Facebook has a Frank Gehry-designed building with a garden roof where employees can walk along a half-mile track, and YouTube has a red slide connecting its second and third floors that can accommodate three people at a time. Alphabet Inc., YouTube’s parent company, is working on a giant terrarium-like campus spanning more than 60 acres.

Visitors are tolerated and sometimes welcomed. Tourists regularly stop to pose for photos in front of the large thumbs-up sign in front of the Facebook campus or the Android statues at Google.

Even as shootings have mushroomed across the U.S., gun violence at work is rare, especially in Silicon Valley. A decade ago, a man who was fired from Santa Clara, California, chipmaker SiPort killed three people, including the chief executive officer and a human resources manager.

Harp, the security consultant, said companies watch every incident closely. “We always learn something you should be doing better.”