When tragedy struck on October 1, 2017, in Las Vegas, Nevada, not only was it the worst mass shooting in U.S. history, but a learning experience for law enforcement on how to deal with a mass casualty incident.
At least 58 people were killed and hundreds more were wounded when a gunman opened fire from the Mandalay Bay Hotel onto a country music festival taking place in a field across the street from the hotel.
The incident and its response were discussed last week at a meeting of the Counterterrorism Preparedness Network, which seeks to bring law enforcement and Homeland Security officials together to prepare for and learn from peers.
"We're an international collaboration of cities," Alex Townsend-Drake, the director of the Counterterrorism Preparedness Network, told ABC News in an interview. "We work across the strands of preparedness and protective security -- very much with a focus on the city environment, but we also work with national and international organizations that are working in this space, and we work across Europe and North America, primarily, but also with federal partners in Australia and New Zealand."
In a "changing" threat environment, the group meets 22 times per year, most recently last week in Washington, D.C. The group also fosters communication with other state and local homeland security and emergency managers to establish best practices for responding to various incidents.
"Whether that's war in the Middle East or it's lone wolf actors attacking synagogues, that is happening around the world," Clint Osborn, the director of the District of Columbia Homeland Security and Emergency Management Agency, told ABC News. "And what we get to do by being part of the network is link up with these partners as they're experiencing things and as they are learning lessons and reaching out, we have a resource that we can ping and get information very, very quickly about what they've learned and how they've adjusted."
Osborn said they can apply real-world information sharing to problems that they are facing. Social media creates a unique threat environment and "amplifies" the threat in some cases.
"We've got counter-terrorism, we've got hostile state activity, we've got non- ideologically motivated violence, we've got criminal and proxy groups. And then amongst all of that, you've got the online space, which compounds that and is actually probably one of the biggest security challenges of our time, and it brings it all together," Townsend-Drake said. "So never has this engagement across borders and across agencies been more important than it is today."
Online, both European and U.S. agencies are seeing a similar "pathway to violence" with young adults, and how "state-sponsored actors" are radicalizing them.
"I think the network is really helpful and important in that it shows us. That even separated by an ocean, we are experiencing a lot of the same things," Osborn said.
The group also incorporates academia to better understand the threat environment.