Even before the killing of four Marines in Chattanooga, Tenn., in an "act of terrorism," Americans revealed a deep concern about Islamic extremism and a very high worry about ISIS, according to the latest poll from Pew Research.

Some 53 percent, more than the average in the non-Islamic world, said they are "very concerned" about Islamic extremism in the United States, said Pew.

RELATED: Obama, FBI split on #TwitterTerror

While the numbers were lower than for some countries in Europe that have experienced domestic Islamic terrorism, they were much higher than a few years ago. In 2011, for example, 32 percent told Pew that they were very concerned.

The slayings Thursday by Muhammad Youssef Abdulazeez, born in Kuwait, could spike those numbers.

RELATED: Ohio man arrested, charged for supporting Islamic State

Pew added that Republicans are more concerned than Democrats, though no reason was given.

"In the U.S., these demographic differences also extend to political party and religion. Republicans and Americans who say religion is important are more likely to be concerned about Islamic extremism than are Democrats and independents, and those who say religion is not important to their daily lives," said the survey analysis.

And the numbers are even higher when it comes to concern about ISIS. Pew said that 70 percent of Americans have a high concern about the movement known for seizing key Iraq territories and beheadings.

RELATED: With no change in ISIS strategy, lawmakers vent frustration

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com. American's terror concern grows http://washex.am/1JmYfQX in Washington Examiner's Hangs on LockerDome