WASHINGTON -- Executives of Facebook, Google and Twitter are telling Congress they've gotten better and faster at detecting and removing violent extremist content on their social media platforms in the face of mass shootings fueled by hatred.

The executives were questioned Wednesday at a hearing by the Senate Commerce Committee. They said they are spending money on technology to improve their ability to flag extremist content and taking the initiative to reach out to law enforcement to try to head off potential violent incidents.

Google's director of information policy says the company will "continue to invest in the people and technology to meet the challenge."

The lawmakers want to know what the companies are doing to remove hate speech from their platforms and how they are co-ordinating with law enforcement.