More than 5,000 security guards working in commercial office buildings in Los Angeles won the right to unionize Wednesday as a tentative agreement was reached between union advocates and building owners, according to the Service Employees International Union released late Wednesday.

The tentative “neutrality” agreement between the SEIU, advocates for security guards and the Building Owners and Managers Association of Greater Los Angeles allows about half the 10,000 commercial building security guards in the city of L.A. to choose whether to form a union with the SEIU, free of interference from building owners or operators.

This agreement follows a smaller pact reached last April between the SEIU and Robert Maguire, the largest commercial office building landlord downtown, that covered several hundred security guards.

Under this most recent agreement, once a majority of the security officers working for each of the private security firms have indicated their desire to form a union with SEIU, the companies will recognize SEIU as the security officers’ union.

Attempts to reach building owners Wednesday evening were not successful.