(CNSNews.com) - Reps. Michael McCaul (R-Texas) and Peter King (R-N.Y.) told separate Sunday news shows that they are very concerned about the possibility of terror attacks over the July 4th holiday.
"There's a great deal of chatter, a high-volume if you will," McCaul, chairman of the House Homeland Security Committee, told "Fox News Sunday."
Rep. King, who chairs a House subcommittee on counterterrorism, agrees: "There's great concern," King told ABC's "This Week." "I would say there's probably more concern now than at any time since September 11th."
A security bulletin issued Friday by the FBI and Homeland Security Department warned local law enforcement to be on alert.
And the United States is not alone: On Monday, British Prime Minister David Cameron told the BBC, "There are people in Iraq and Syria who are plotting to carry out terrible attacks in Britain and elsewhere, and as long as ISIL exists in those two countries, we are at threat."
McCaul said the concern stems from a "confluence" of events: "ISIS spokesman calling for jihad during Ramadan, which is happening right now. You have the one-year anniversary of the caliphate or Islamic State; and now we have the Fourth of July coming up, which is one of the holidays we celebrate that they like to target this sort of thing and these anniversaries.
"So, I think given the confluence of events, we're being on the cautious side here to warn the public to remain vigilant, to enjoy the Fourth of July parades, but remain vigilant during these celebrations," McCaul said.
King said national security officials are worried about lone wolves as well as the potential for a coordinated terror attack.
And he said there's a reason Homeland Security Secretary Jeh Johnson issued a statement last Friday urging Americans to "remain vigilant."
"They don't put those statements out that far in advance, unless there's reason for concern," King said.
King described ISIS as "incomparable" in its ability to reach the "disaffected," the "deranged" and the "ideologically committed."
"I mean, it's no coincidence that you've seen a series of arrests here in New York of terrorists over the last week to 10 days. This is not just something that's happening by coincidence."
ABC's Pierre Thomas reported on Sunday that the FBI is stepping up arrests across the country. "They're not waiting for cases to fully mature. If they can build a case, they're going to bring you in right now," Thomas reported.
McCaul told "Fox News Sunday" that the federal government has stopped 50 terror plots in the last 12 months.
"I'm extremely concerned about the way these Syrian ISIS recruiters can use the Internet at lightning speed to recruit followers in the United States with thousands of followers in the United States and then activate them to do whatever they want to do whether it's military installations, law enforcement or possibly a Fourth of July event parade.
"That's I think what concerns me the most, and in light of the three attacks in three hours on three continents overseas, shows us that ISIS is not just regionalized like the administration says only in Iraq and Syria, but rather demonstrates a global threat that they can conduct external operations and they are very savvy at doing that over the Internet."
Terrorists on Friday attack a U.S.-owned chemical factory in France, a beach resort in Tunisia, and a mosque in Kuwait, all within a few hours of each other.
McCaul said all of the attacks were motivated by ISIS. "They are, in fact, carrying out the ISIS mission. And I think in all three incidents, ISIS was the driving force behind the attacks. And these were very significant attacks, some of the worst we've seen in three different continents. The idea that they could do this, and now, the external operations potentially into the United States by use of the Internet.
"This is not bin Laden with courriers now. This is a new generation of terrorists using the Internet in a very savvy way to attack the West and also get in the homes and in the basements in the United States to radicalize individuals and then call them up as sleeper cells to attack Americans."