A Twitter account associated with ISIS, also known as the Islamic State, threatened on Sunday night to assassinate Twitter employees in San Francisco for closing down their accounts, warning them that they would "bring the war" to San Francisco, according to a number of news outlets.

Since ISIS recently killed two American journalists and threatened to behead a British citizen for the UK's participation in efforts to stem ISIS's growth, Twitter has been attempting to crack down on accounts associated with the terrorist group by deleting propaganda posts, including disturbing videos of executions, according to Vocativ, one of the first outlets to pick up the story.

The call for retribution against the social media company is believed to have come from the now-suspended account, @dawlamoon, which was purportedly linked to Al Nusra Al Maqdisia (The Supporters of Jerusalem), a Jerusalem-based group that pledged its allegiance to ISIS in February. It wasn't clear what, if any, formal ties the group had to ISIS, SFGate reported.

Although the tweets were all written in Arabic, Vocativ translated them.

"The time has arrived to respond to Twitter's management by directly attacking their employees and physically assassinating them. Those who will carry this out are the sleepers cells of death," one tweet read.

"Twitter management should know that if they do not stop their campaign in the virtual world, we will bring the war to them in the real world on the ground."

"Every Twitter employee in San Francisco in the United States should bear in mind and watch over himself because on his doorstep there might be a lone wolf assassin waiting," read another.

And finally, they urged Europe to join the pledge: "#AttackingTwitterEmployees is on the agenda of mujahedeen and lone wolves who are across Europe."

All of the tweets were accompanied by a hashtag that translated to "the concept of lone wolf attacks."

With the freedom of speech premise that underlies Twitter, keeping control on extremist propaganda gets almost impossible, UK MailOnline reported.

Hence, the social network has specifically been a crucial platform for the jihadis to promote their warped interpretation of Sharia law, to recruit new members, boast of its activities and make ISIL-related hashtags trend.

Meanwhile, Twitter wouldn't reveal whether it was beefing up security at its downtown San Francisco headquarters, saying only that it's "security team is investigating the veracity of these threats with relevant law enforcement officials," according to SFGate.