DHS official: No plans to change security measures after Manchester attack Authorities continue to assess whether additional measures are needed.

 -- After Monday's bombing that killed 22 people and injured 59 others at an Ariana Grande concert in Manchester, England, there are no plans to make significant security changes in the United States, according to a Department of Homeland Security official.

The official said that the federal security posture in the U.S. is already at high levels and that there is not much more to be done in the aftermath of the attack, allegedly carried out by 22-year-old Salman Abedi with an improvised explosive device outside the concert at the Manchester Arena.

The official insisted that federal authorities will continually assess whether new measures are warranted.

ABC News has additionally learned that state and local fusion centers across the country — which include representatives from local, state and federal agencies — are working to identify potentially vulnerable open venues and upcoming events in their regions so they can help local police update security plans for those sites and events.

The FBI held a call Tuesday afternoon with the heads of FBI field offices nationwide and leaders from state and local law enforcement agencies across the country to lay out what it knows so far about the Manchester attack and to urge vigilance.

FBI made clear that while the agency isn't aware of a specific, credible threat to the U.S. homeland, authorities must remain vigilant and report any suspicious activity to the FBI or other appropriate authorities.