Pro-Hamas extremists are flooding social media platforms with calls for attacks on Jewish communities and other targets in the U.S. and Europe, prompting U.S. law enforcement agencies to step up their readiness postures amid deep concerns about possible violence, American officials and private analysts told NBC News.

Tuesday’s explosion at a hospital in Gaza is threatening to become a flashpoint, they said, with posts on X and other platforms portraying it as an Israeli atrocity using an American-made bomb, despite an assessment from U.S. intelligence agencies that the damage resulted from an errant missile fired by a Palestinian militant group.

Groups linked to Al Qaeda and American neo-Nazis have been seeking to exploit the ongoing war to encourage attacks, according to two separate intelligence products obtained by NBC News.

“You must attack them in their homes, shops, posts and places of amusement … Tear their bodies apart, let their blood flow and take revenge for your martyrs,” said one Al Qaeda post quoted in an intelligence bulletin by the New York Police Department, which has maintained a global intelligence network since 9/11.

A Homeland Security official told NBC News that the DHS is monitoring a “heightened threat environment” in the U.S. and is concerned about attacks on Jewish-Americans, as well as Arab-Americans and Muslim-Americans.

A separate intelligence bulletin by the Institute for Strategic Dialogue, a think tank that monitors extremism on the web and feeds information to law enforcement agencies, said Al Qaeda-linked groups and others posted a series of messages in response to the Gaza hospital incident, calling for attacks on U.S. and Israeli embassies and other targets.