Apple was the subject of heated protest Thursday — and not just from those frustrated they didn’t land an invite to the company’s much-hyped press conference next month. Police hauled away a dozen activists from Apple’s Stockton Street store, where they held a sit-in protesting low wages and poor working conditions for security guards at Apple and other tech companies.

Organized by SEIU Service Workers West, the demonstrators were upset with Security Industry Specialists, Inc., colloquially known SIS, a company that contracts security services for many tech companies. They say that while tech companies are making huge money, security workers are not sharing in the bounty. A report out this week from Working Partnerships USA titled “Tech’s Diversity Problem: More than Meets the Eye” explores this underclass of service workers that is growing in Silicon Valley.

The report says:

These twin dynamics – lack of access to high-end tech jobs, and lack of adequate wages in

contracted service jobs – have a profound impact on the communities that are left behind by

Silicon Valley’s flagship industry. There is an ever-increasing divide between the region’s wealthy

and everyone else.

SIS counters that its workers are among the best paid in the business, saying it was the target of a “vicious ‘corporate campaign’” by SEIU.

At Thursday’s protest many held signs that said “Invisible No More.” Kayla Gordon, 24, a former SIS security guard who now works as an organizer for SEIU, said that while she made $15-an-hour when she worked for SIS, she only worked a few hours a week and had few benefits.

“We say we’re invisible because you work here, you’re protecting their products — but it’s like people don’t even see you,” said Gordon. “You work at these big companies that make a lot of money, but you don’t get any of that.”

Here is Gordon, speaking outside the store after the protesters had been carted away: