Families of three victims killed in the Dec. 2, 2015, San Bernardino terrorist attack sued three media giants Wednesday, accusing Twitter, Google and Facebook of "knowingly and recklessly" providing Islamic State with a platform for years to spread propaganda, raise funds and attract new recruits.

Families of three victims killed in the Dec. 2, 2015, San Bernardino terrorist attack sued three media giants Wednesday, accusing Twitter, Google and Facebook of "knowingly and recklessly" providing Islamic State with a platform for years to spread propaganda, raise funds and attract new recruits.

The federal lawsuit seeks unspecified damages on behalf of relatives for Sierra Clayborn, Tin Nguyen and Nicholas Thalasinos. Each were San Bernardino County Department of Public Health employees and co-workers of shooter Syed Rizwan Farook.

Filed in U.S. District Court's Central District of California, Western Division, the suit alleges that Twitter, Facebook and Google, through subsidiary YouTube, were liable for aiding and abetting acts of international terrorism and providing material support to terrorists, among other violations.

The companies are accused of having "provided the terrorist group ISIS with accounts to use its social networks as a tool for spreading extremist propaganda, raising funds, and attracting new recruits," the lawsuit reads. "This material support has been instrumental to the rise of ISIS and has enabled it to carry out or cause to be carried out, numerous terrorist attacks, including" the San Bernardino attack, which killed 14 and injured 22.

A Facebook spokesperson said Thursday that the company is committed to providing a service where users feel safe.

"There is no place on Facebook for groups that engage in terrorist activity or for content that expresses support for such activity, and we take swift action to remove this content when it's reported to us," the spokesperson said via email. "We sympathize with the victims and their families."

Twitter and Google didn't directly respond to emails requesting comment.

But Twitter, which has rules prohibiting threats of violence and the promotion of terrorism, has suspended 636,248 accounts between Aug. 1, 2015 and Dec. 31 for violations relating to promoting terrorism. Between July 1 and Dec. 31 alone, Twitter suspended nearly 377,000 accounts.

Yet attorneys for the plaintiffs claim in the lawsuit that ISIS accounts on Twitter had grown at an "astonishing rate" since 2010 and, until recently, its official accounts were unfettered.

If it weren't for Twitter, Google and Facebook, attorneys argued, "the explosive growth of ISIS over the last few years into the most feared terrorist group in the world would not have been possible."

Similar court complaints have been filed in the Pulse nightclub attack in Orlando where 49 people were killed and in the attacks in Paris that killed 130.

In a June 18 report by Fortune on the Paris attacks lawsuit, interviews with legal experts by Ars Technica were cited to explain how that suit likely had little chance to succeed.

The 1996 Communications Decency Act "establishes that user-generated content on digital platforms cannot be used in proceedings against the platforms," Fortune noted.

Shea Johnson can be reached at 760-955-5368 or SJohnson@VVDailyPress.com. Follow him on Twitter at @DP_Shea.