SEATTLE -- King County has hired a new private security firm to patrol the Downtown Seattle Transit Tunnel, replacing the firm whose guards watched while a teenage girl was beaten in an attack caught on surveillance cameras.

County Executive Dow Constantine announced Thursday that Securitas Security Services USA guards will replace those of Olympic Security over the next 45 days.

Securitas guards will report suspicious or inappropriate behavior, look out for safety or security problems in the tunnel and assist passengers, among other duties, Constantine said in a news release.

Metro will continue to use personnel from Olympic Security to carry out other, more limited security tasks. Olympic guards recently received additional training in defusing potential physical conflicts, and will continue to provide security in the tunnel during the transition to Securitas.