Sen. Maria Cantwell, a Democrat from Washington, quizzed Facebook CEO Mark Zuckerberg today over his employees' dealing with Cambridge Analytica, a political data firm with ties to President Donald Trump's campaign.

Asked whether Facebook employees were involved with Cambridge Analytica during the 2016 presidential campaign, Zuckerberg said he didn't know, though they did "help out."

"Although, I know we did help out the Trump campaign overall in sales support in all in same way that we help do with all other campaigns," he said.

Why we're talking about Cambridge Analytica

Last week, Facebook said Cambridge Analytica may have had information on about 87 million Facebook users without the users' knowledge. Previous reporting had put the number of users at about 50 million.

The data obtained was originally collected by University of Cambridge professor Aleksandr Kogan who used an app called "thisisyourdigitallife," which offered a personality test. Facebook users who downloaded the app granted it permission to collect data on their location, friends and things they Liked. The data collection was allowed by Facebook at the time.

However, Facebook has said that Kogan violated its terms of service by giving the information to Cambridge Analytica.

Facebook banned Kogan and Cambridge Analytica from its platform last month ahead of a New York Times investigative report about how the data was passed on.