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Shuttle buses carrying Apple and Google employees were apparently vandalized Tuesday while traveling to and from the South Bay, officials said. No injuries were reported.

Five buses driving in the northbound and southbound directions of Interstate 280 between Highway 84 and Highway 85 were damaged during the Tuesday morning and evening commute, said California Highway Patrol Officer Art Montiel.

Four buses were chartered by Apple and one by Google, the officer said. The Apple campus is located off I-280 in Cupertino. Google headquarters is in Mountain View off Highway 101.

According to Montiel, several bus windows were damaged and cracked, possibly by pellet guns, BB guns or rocks.

"The outside pane was broken, but it didn't shatter the window," he said.

There is no indication these were targeted incidents, Montiel said, because the buses are not labeled with their companies or destinations.

Apple and Google did not immediately respond to SFGATE's requests for comment.

News site Mashable obtained a copy of an internal email sent to Apple employees following the Tuesday incidents.

"Due to recent incidents of broken windows along the commute route, specifically on highway 280, we're re-routing coaches for the time being," the email said. "This change in routes could mean an additional 30-45 minutes of commute time in each direction for some riders"

Even if the unmarked buses were to reroute, Montiel said, "we all know what these buses look like."

"If anyone was trying to target the buses, they could identify them on other freeways," he said.

The corporate buses, used to transport employees from San Francisco to South Bay campuses, have been targeted by vandals in the past.

Protests against the buses, which some deem symbols of gentrification, broke out across the Bay Area in 2013, with protesters blocking the passage of the vehicles on multiple occasions. In an incident in late December 2013, a Google bus' windows were broken and tires slashed.

Michelle Robertson is an SFGATE staff writer. Email her at mrobertson@sfchronicle.com or find her on Twitter at @mrobertsonsf.