Transcript for US stepping up security in several public spaces

Tonight, many back home in the U.S. Asking, what about concert there is? Even sporting events? The FBI held an urgent call with field offices. ABC's justice correspondent Pierre Thomas tonight. Reporter: Tonight, ABC news learning that state, federal, and local authorities are now working to identify potentially vulnerable "Open venues" here, ranging from sporting events to concerts. At a John legend concert in Grand Prairie, Texas, last night, as Manchester unfolded -- We want to make sure they saw plenty of officers out here. Reporter: -- Beefed up security. At the Melissa Etheridge concert in Los Angeles, same story. More security, bags being inspected. I understand why they have to do that. It's the world that we live in now. Reporter: With terror attacks surging in Europe, U.S. Officials locked in. Worried about ISIS and the potential for copycats. Expect increased security at this weekend's indy 500. Today in New York, the nation's number-one terror target, more heavilmed police at more locations. Pierre, we just heard Brian Ross reporting earlier, there are some 500 people being watched here in the uk because of potential terror links. But you reported there are countless cases back in the U.S. That authorities are watching as well. Here at home, the they're conducting more than 1,000 terror cases in all states. Pierre Thomas in times square tonight.

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