“Over the last two years, more and more people have been using Facebook to discover products and to buy and sell things to one another. We are continuing to develop, test, and launch new products to make this experience even better for people and are updating our regulated goods policies to reflect this evolution,” Monika Bickert, head of Facebook’s global policy management, said in a statement on Friday evening.

President Barack Obama and state attorneys general, as well as gun control activist groups Moms Demand Action for Gun Sense in America and Mayors Against Illegal Guns – backed by billionaire and former New York Mayor Michael Bloomberg – had been urging the world’s top social media website to crack down on private gun sales, USA Today reported.

‘Hood rats’ and Tasers: NYPD cop outed for incendiary social media posts https://t.co/uWgrYt8Twk pic.twitter.com/PuGNqjPIGm — RT America (@RT_America) January 15, 2016

The last time Facebook took gun-related action was in March of 2014, when it blocked posts involving gun transactions to minors and required user-controlled pages to adopt wording telling others to obey local and federal laws and regulations. The site already bans arranging sales of marijuana, pharmaceuticals, and illicit drugs.

The one exception to the rule is licensed dealers, who can keep their businesses advertised, though online sales will still be prohibited.

With 1.6 billion visitors each month, Facebook is expanding its marketplace capabilities, providing digital payment services and instant transfers via personal messaging. The users that make up that emerging marketplace will also serve as lookouts for banned gun sale posts, according to the New York Times.

Some users, however, are not so likely to help enforce the new rule, which they see as a violation of their rights, or an example of the website’s political bias or hypocrisy.

What the fuck of all fucks.Facebook has banned private gun sales groups… Uet it is perfectly acceptable for isis… Posted by Michael James Rullo on Friday, January 29, 2016

So I guess all gun sales on fb will now occur using slang, code words, and subterfuge. Posted by Robert Duhaime on Friday, January 29, 2016

Facebook says they are banning private gun sales so I want to test them. Anyone interested in an AK with accessories? $1,500 cash and a copy of your picture ID. No felons and 18+. Posted by Cory King on Friday, January 29, 2016

The Facebook police are REAL folks. Took less than 12 hours for me to receive this message after posting my AK for sale. Just something to think about. Posted by Cory King on Saturday, January 30, 2016

Facebook will first remove posts violating the new rule and then possibly take action against the user, depending on the situation, the Times reported.

Facebook joins other services like Craigslist, which don’t also allow gun sales either. Many ad services such as Google AdWords prohibit the promotion of weapons as well, The Verge reported.