A gunman who opened fire at a New Jersey mall Monday night later holed up in a back room and shot himself in the head , authorities say . No one else was injured in the mall shooting . Richard Shoop 's body was found at 3:20 a.m. Tuesday in an obscure part of Westfield Garden State Plaza mall , hours after he fired at least six bullets without striking anyone in the massive shopping center . He acted alone , authorities say . `` We know that his intent was either suicide or to do something that would cause police to shoot him , which we call 'suicide by cop , ' `` Bergen County Prosecutor John Molinelli told CNN 's `` New Day . '' `` He had more than enough opportunity to be able to shoot other people , '' including a group adjacent to him , but he did n't , Molinelli said . `` Instead , he shot randomly at different locations . '' Shots hit the ceiling , an escalator , an elevator and a storefront , the prosecutor said . The reasons for the shooting remain unclear . Shoop used narcotic drugs and sold drugs as well , Molinelli said . And he left behind a note referring to the idea that the `` end was coming , '' Molinelli said . `` That could mean going to jail , getting arrested , or it could mean suicide . '' Authorities do n't know whether Shoop left the note immediately before going to the mall . Shoop 's brother , Kevin , called authorities after hearing about the shooting and said he thought Shoop might be the gunman , Molinelli said . Police did not confirm the shooter 's identity until they found his body . `` We 're not sure exactly what caused him to do this , and we 're all devastated , '' Kevin Shoop told reporters Tuesday . `` My brother intended to harm nobody else but himself . He just , sadly , decided to make ... an act of self-indulgence by taking his own life publicly . And it 's a tragedy to us all , '' he said . Pandemonium . The melee started about 9:20 p.m . ET Monday night , just as the shopping center was about to close . Thousands of people were still in the mall , Molinelli said . Shoop , dressed all in black and wearing a motorcycle helmet , walked through the mall with a rifle modified to look like an AK-47 . The rifle was taken from Shoop 's brother , Molinelli said . Allie Cozic , who works in the mall , said everyone was `` running to wherever they could . '' `` It was almost like when you 're watching a horror movie and the killer is walking slowly . That 's what it seemed like , '' she said . `` He was wearing all black . It almost looked like body armor of some kind . As soon as I saw the gun , I just turned and ran . '' Eddie Kahmann , another mall employee , said he heard six or seven gunshots . `` There was just people running like crazy , so I quickly just closed my doors , ran to the back , turned off all the lights , music and everything , just to stay hidden , '' he said . The shooting sent panic through the mall and set off a frenzied hunt for the gunman . In the early hours of the search , officials were n't sure whether the shooter was still inside or outside the 2 million-square-foot building . Officers did not fire any shots , Molinelli said , and there was only slight damage to the mall . Even as Shoop 's body lay in a remote room in a construction area , fear permeated the mall . More than 100 shoppers were still hiding inside stores early Tuesday morning , unsure of whether they could safely come out . Officers worked to evacuate each store . Signs of trouble . Shoop , 20 , was known by local law enforcement . He had a history of drug use and abuse , Molinelli said . `` He at least thought that he was reaching a point where there was no recourse but to take his own life , '' Molinelli said . The owner of a pizza shop where Shoop had been working for about a year said he was a good , trustworthy worker . Dod Geges , owner of Victor 's Pizza Shop , describes Shoop as a nice , quiet guy . But in the last two weeks , `` something was off '' about Shoop , Geges said , adding that he `` was n't his usual self . '' Geges ' brother Robert Gega , who manages the restaurant , said Shoop was working 60 hours a week and `` sobering up . '' `` He was n't drinking or drugging , '' Gega said , adding that Shoop had good friends and never gave an indication of contemplating suicide . `` He would never hurt anyone . '' LAX shooting : Latest on the suspect , victims and warning that may have come too late .
`` We 're all devastated , '' says gunman 's brother . The brother called authorities after hearing about shots at the mall . The gunman is identified as 20-year-old Richard Shoop . No one else was injured .