Facebook Inc. said an increasing number of users are posting fliers and images using violent or incendiary language to promote gatherings across the country over the next week, echoing warnings from law enforcement that there could be another attack similar to last week’s riot at the U.S. Capitol.

A Facebook spokeswoman said the social network is tracking “dozens” of fliers promoting events on Jan. 17, Jan. 18 and Jan. 20, the date of President-elect Joe Biden’s inauguration. The company is removing the postings using image recognition technology, and many of the images calling for the gatherings in Washington and elsewhere have been flagged to Facebook by a group of partner organizations that track terrorism and cybercrime.

“We work with experts in global terrorism and cyber-intelligence to identify calls for violence and remove harmful content that could lead to further violence,” the spokeswoman said. “We are continuing all of these efforts and working with law enforcement to prevent direct threats to public safety.”

Facebook has banned “over 250 white supremacist groups” from its services, and is working to “prohibit QAnon and militia groups from organizing on our platform,” the spokeswoman said.

After rioters supporting President Donald Trump stormed the U.S. Capitol on Jan. 6, Facebook suspended Trump from its services for fear his rhetoric could lead to more violence. Chief Operating Officer Sheryl Sandberg said this week that the violent riot was “largely organized” on other services. Many of the groups involved have historically used the social network to recruit and promote their messaging.

Facebook considers the U.S. Capitol riot to be a violating event under its “dangerous individuals and organizations policy,” meaning content praising the event will be removed.