Six people were killed and at least 30 others were wounded in a mass shooting at a Fourth of July parade in the Chicago suburb of Highland Park, Illinois, reports ABC News.

According to video footage released by the authorities, Robert Crimo III was taken into custody without incident eight hours after the massacre. He climbed to the roof of a business using a ladder in an alley before shooting into the crowd.

ABC News 7 reported that Crimo is from the area. Witnesses claimed he lives in Highland Park, Illinois. 

"I've definitely heard his name before. I know that he's a Highland Park resident, and went to Highland Park High School," said Lauren Sachs, who witnessed the shooting.

His father, Robert Crimo Jr., previously ran for mayor of Highland Park in 2019.

As authorities examined his social media, it was discovered that Crimo performed as a rapper named “Awake,” whose recent music videos included depictions of mass murder. He's posted several videos of himself trapped in an American flag following school shootings.

On Discord, he posted a picture of Budd Dwyer, the Pennsylvania state treasurer who shot and killed himself on live television in 1987 along with the caption, “I wish politicians still gave speeches like this.”

Highland Park Mayor Nancy Rotering said Crimo’s online postings “reflected a plan and a desire to commit carnage for a long time in advance.”

“And it's one of those things where you step back and you say, 'What happened? How did somebody become this angry, this hateful?' To then take it out on innocent people who literally were just having a family day out,” Rotering added.

In the aftermath of the shooting, the NorthShore University Health System has treated 38 victims with injuries who were taken to hospitals by ambulance or other vehicles.

Witnesses to the massacre explained their accounts of the tragic incident.

"I thought that it was the Navy that was saluting the flag with the rifles. But then when I saw people running, I picked up my son and started running," one witness said.

"We ran behind the building and I put my son in a dumpster ... and I went back to look for the rest of my family," he continued. "It was just horrible."

Illinois Rep. Brad Schneider, who was at the start of the parade when the gunfire rang out, released a statement about the incident.

“Today a shooter struck in Highland Park during the Independence Day parade,” his tweet read. “My campaign team and I were gathering at the start of the parade when the shooting started. My team and I are safe and secure. We are monitoring the situation closely and in touch with the Mayor.”

“There are no words for the kind of monster who lies in wait and fires into a crowd of families with children celebrating a holiday with their community,” continued Gov. JB Pritzker in a statement. “There are no words for the kind of evil that robs our neighbors of their hopes, their dreams, their futures."

"Prayers alone will not put a stop to the terror of rampant gun violence in our country," the governor wrote. "We must—and we will— end this plague of gun violence."

President Joe Biden said in a statement that he and his wife Jill were "shocked by the senseless gun violence that has yet again brought grief to an American community on this Independence Day."

 "I’m not going to give up fighting the epidemic of gun violence," added the President of the United States.