In 2007, YouTube had moved its headquarters from San Mateo, California to San Bruno, on Cherry Avenue next to Interstate 380. The main building was initially built for Gap Inc. in 1997. It had been designed in 1994, has a green roof, and was built with energy efficient ventilation systems.</ref> Across more than six properties, YouTube has over 1,700 employees working in the city, and is San Bruno's largest employer. On April 3, 2018, a shooting took place at the headquarters complex, leaving four wounded and the female shooter dead.