(NewsNation) — In the wake of a mass shooting at an Independence Day parade in a Chicago suburb that left six people dead and at least 30 wounded, experts outlined the challenges of preventing such a tragedy: from social media monitoring to gun control to presidential-like security protocols.

Federal law enforcement officials were on high alert because of a “heightened environment” fueled in part, they said, by domestic extremists and social upheaval.

Before a shooter fired from a rooftop in Highland, Illinois, killing six and injuring at least 30, the Department of Homeland Security recently indicated that there was potential for another spate of violence in the foreseeable future. Authorities said extremists and so-called “lone actors” could become animated by events and issues ranging from the House’s ongoing Jan. 6 hearings to controversial Supreme Court rulings.

Phil Andrew, a former FBI special agent and co-founder of Pax Group, said pre-incident planning goes into great detail to lay out routes and ensure that traffic is controlled ahead of events like community parades. Following Monday’s shooting, authorities may consider emergency evacuations in their future planning.

“Maybe even some pre-incident reviews, where you’re going through buildings and rooftops to make sure that you don’t see anything unusual,” Andrew said. “Some events already include that, but I think that’s probably something that law enforcement can be considering with big events.”

He continued: “A critical element of what the Secret Service does to protect the president is they look at folks that are in the area that have troubled mental health or created some sort of criminal activity in the past, and they account for them before the events happen, where they bring the president in.”

The Highland Parkshooter sprayed the crowd with gunfire, which was initially mistaken for fireworks before hundreds of panicked revelers of all ages fled in terror. Police later took Robert E. Crimo III — who they call a person of interest — into custody several hours after the shooting.

“I think what we continue to be surprised by is the easy availability of dangerous weapons like this to use,” Andrew said. “Even in states where efforts have been made to try to restrict access, the surrounding states undermine those rules.”

Michael Alcazar, a retired New York Police Department detective, says law enforcement officials may have to start rethinking soft targets.

“Active shooters have become more prevalent in the nation and we have to prepare for it. We have to be more vigilant. The police have to be more proactive,” he said. “The police did a good job apprehending the perp, but what did they do before the parade? How did this guy walk in with a ladder, did he bring it the night before? Did you bring it during the parade? I’m sure people saw him putting the latter and climbing up; someone should have reported that. Police should have spotted that. He shouldn’t be so comfortable to carry his weapon, probably in a bag, and a ladder put it up against a building and climb up.”

According to the Gun Violence Archive, 313 mass shootings have happened in the U.S. so in 2022. As that number continues to rise, gun control advocates say there is an urgent need for lawmakers to raise the minimum age to buy certain guns, like military-style assault weapons, to 21.

“The last few mass shootings that hit a high profile like this have all been executed by young people who demonstrated some sort of dangerous or bizarre behavior, and probably should not have had access to weapons in the first place,” Andrew said.

Federal law already restricts those under 21 from buying a handgun. However, the legal age to purchase a long gun is 18.

New York, Florida, California, Hawaii, Illinois, Vermont and Washington, all prohibit the sale of semi-automatic rifles to anyone under the age of 21. Florida implemented the law after a teen gunman opened fire at a Parkland high school in 2018 killing 17 people.

Crimo, who goes by the name Bobby, was an aspiring rapper with the stage name Awake the Rapper, posting on social media dozens of videos and songs, some ominous and violent.

Several lawmakers have raised questions about whether they should more readily look at a person’s online history of violence, and consider that a component of a suspected killer.

“That’s really where we need greater work in prevention, is the community needs to alert law enforcement to these types of social media utterances that are concerning,” Andrew said. “But we also, I think, need to see the social media companies themselves do more to regulate what they post and what they see on their channels.”

In New York, state lawmakers approved sweeping legislation Friday that would ban concealed weapons from so-called “sensitive locations” like Times Square, public transit and other venues — while requiring gun permit applicants to give the state information about their social media accounts and character references. 

The Associated Press contributed to this report.