Six buses operated by Silicon Valley tech companies to shuttle employees to their offices have been attacked on the highway over the past week. The California Highway Patrol reports that four Apple and one Google bus had their windows shattered on Tuesday by unidentified projectiles; the patrol suggests that they could have been rocks or bullets from a pellet gun. Another Apple bus also had its window damaged on Friday. No injuries were reported.

The company has filed a police report with a description of a suspect, according to TechCrunch, and is now rerouting its buses, prolonging the commute by 30 to 45 minutes. Google is taking similar steps. Facebook told TechCrunch that its buses have not faced similar problems.

Highway patrol spokesman Art Montiel said that the assailant appears to singling out the tech companies in particular, as Greyhound and other buses in the area have gone unscathed. Montiel told The Guardian, “If someone was targeting the buses I’m sure they are going to find them anywhere they go. It’s not like they are hidden.” Google and Apple’s buses are unmarked, though they are identifiable by color.

Locals have in the past channeled their hostilities at tech commuter buses, which to some represent the rising cost of living and heightened economic inequality that Silicon Valley’s expansion has unleashed on the Bay Area. In 2013, a protestor smashed the window of a Google bus in Oakland and handed passengers fliers reading, “Get the fuck out of Oakland.” Protestors surrounded another Google bus in 2014 for half an hour, which apparently spurred the company to start employing private security guards to help escort commuters to their workplaces.

The California Highway Patrol for Redwood City issued a press release on the matter:

Slate has reached out to Apple and Google for comment, and to the California Highway Patrol and local police, and we will update this story if we receive a response.