FBI Director Christopher Wray warned on Tuesday that Hamas’ rampage inside Israel could inspire violence in the U.S., telling lawmakers that multiple foreign extremist groups have called for attacks against Americans and the West in recent weeks.

“We assess that the actions of Hamas and its allies will serve as an inspiration the likes of which we haven’t seen since ISIS launched its so-called caliphate years ago,” Wray said, using an acronym for the Islamic State group.

In his testimony before the Senate Homeland Security Committee, Wray gave his most detailed and ominous assessment of potential threats to the U.S. since the Oct. 7 attack by Hamas on Israeli soldiers and civilians.

His reference to the Islamic State, a reminder of when the FBI scrambled to disrupt hastily developed plots of violence by people inspired by the group’s ascendancy, underscores the bureau’s concerns that the current Middle East conflict could create a similarly dangerous dynamic.

Though the FBI isn’t currently tracking an “organized threat” inside the United States, law enforcement is concerned about the potential of attacks by individuals or small groups, as occurred during the rise of the Islamic State in Syria and Iraq a decade ago.

The bureau has already seen an increase in attacks on overseas military bases and expects cyberattacks targeting American infrastructure to get worse as the conflict expands, he said.

“It is a time to be concerned. We are in a dangerous period,” Wray said. “We shouldn’t stop going out, but we should be vigilant.”

Department of Homeland Security Secretary Alejandro Mayorkas, meanwhile, said his agency has responded to an increase in threats against Jewish, Muslim, and Arab American communities in the U.S. since the Oct. 7 attack.

“Hate directed at Jewish students, communities and institutions add to a preexisting increase in the level of antisemitism in the United States and around the world,” he said.

Democratic Sen. Maggie Hassan said Jewish leaders in her state of New Hampshire say congregants are scared to go to synagogue, and Republican Sen. Rick Scott of Florida has heard similar fears from people in his state.

“I know our Jewish families all across my state and all across the country are pretty scared to death right now,” Scott said.

Wray cited sobering statistics in his response, saying that Jewish people make up 2.4% of the U.S. population but are the targets of about 60% of religious-based hate crimes. “That should be jarring to everyone,” he said.

The FBI has also opened a hate-crime investigation in the death of a 6-year-old Muslim boy who police say was stabbed to death by his landlord in an attack that also seriously wounded his mother, Wray said. Police and relatives have said the victims were singled out because of their faith and as a response to the war between Israel and Hamas.