Protesters in San Francisco have stopped a bus filled with Apple employees on their way to work. They've also stopped a Google bus in Oakland.

We're hearing about the blockades via Twitter.

This is the second time this has happened this month. Two weeks ago, protestors stopped a Google bus.

Tech companies like Google, Apple, and Facebook provide buses that take their employees from San Francisco to their headquarters in the suburbs. The buses are free and equipped with WiFi. It's one of those things that is a perk, but also helps employees get more work done.

Protesters are mad at the tech companies for a few reasons.

First and foremost, the wealthy tech employees have driven up the price of housing in San Francisco, which is pricing out some people.

Secondarily, the buses use public transit stops, and some protesters think that's wrong.

The last time this happened, the protesters posted demands that included tech companies kicking in $1 billion for affordable housing.

Here are some photos/tweets:

BREAKING: San Francisco protesters commandeer another tech bus, this time from Apple. #tech @BuzzFeed pic.twitter.com/wtFW28Nzv6 — Joe Fitz Rodriguez (@FitzTheReporter) December 20, 2013

Protesters at SF tech bus blockade: pic.twitter.com/ql7yvUZPD8 — alexei oreskovic (@lexnfx) December 20, 2013

Another bus protest in SF. Labeled Ridgeview. May be Apple. Protestors aren't sure and say it doesn't matter. pic.twitter.com/1j64S3Xt9v — Katy Steinmetz (@katysteinmetz) December 20, 2013

Protesters blocking the Google bus at MacArthur BART station in Oakland. #googlebus #protest pic.twitter.com/dklgVTM6BD — Urban San Jose (@urbansanjose) December 20, 2013