Police officers keep watch outside YouTube’s headquarters Tuesday in San Bruno, Calif., after a woman opened fire on workers there. The woman, who wounded three people and died of an apparently self-inflicted wound, had vented her frustration with YouTube’s recent decision on advertising revenue.

Police officers keep watch outside YouTube’s headquarters Tuesday in San Bruno, Calif., after a woman opened fire on workers there. The woman, who wounded three people and died of an apparently self-inflicted wound, had vented her frustration with YouTube’s recent decision on advertising revenue.