Disturbing footage has emerged of suspected Florida high school killer Nikolas Cruz doing target practice in a backyard while shirtless and wearing a Make America Great Again cap.

In the video, which was taken by a neighbor and obtained by CNN, the teenager can be seen wearing the MAGA cap and socks while pumping off rounds in the yard.

The teenager can be seen in the video firing the gun several times outside before securing it in the waistband of his shorts and heading back inside the home.

It is unclear exactly when the video was taken but it is believed to have been just months before the deadly high school massacre.

A neighbor filmed Nikolas Cruz doing target practice in a backyard while shirtless and wearing a Make America Great Again cap in the months before the deadly Florida high school shooting

Cruz is seen briefly outside appearing to fire shots before retreating into the home

The footage emerged the day after Cruz was arrested for shooting dead 17 people at Florida's Marjory Stoneman Douglas High School on Wednesday.

Broward County Sheriff Scott Israel revealed late on Thursday that Cruz had confessed to carrying out one of the nation's deadliest school shootings and carried extra ammunition in his backpack.

Cruz told investigators he brought more loaded magazines to the school and kept them in the backpack until he got on campus.

He also said he heard 'demon voices' who told him to carry out the deadly attack, according to law enforcement sources who spoke to ABC News.

A fuller portrait of the shooter is still emerging as he is being painted as a loner who had worked at a dollar store, joined the school's ROTC program and posted photos of weapons on Instagram.

Authorities have not offered any specific motive for the shooting, except to say that Cruz had been expelled from the high school.

Students who knew him described a volatile teenager whose strange behavior had caused others to end friendships with him.

Dakota Mutchler, a 17-year-old junior, said he used to be close friends with Cruz but hadn't seen him in more than a year after he was kicked out of the school.

'He started progressively getting a little more weird,' Mutchler said.

Mutchler recalled Cruz posting on Instagram about killing animals and said he had talked about doing target practice in his backyard with a pellet gun.

Nikolas Cruz was arrested on Wednesday for killing 17 and injuring more than a dozen in a school shooting on Wednesday in Florida

Cruz was ordered held without bond at a brief court hearing on Thursday where he wore an orange jumpsuit with his hands cuffed at his waist

This photo posted on the Instagram account of Nikolas Cruz shows a haul of weapons and a bullet proof vest lying on a bed

The 19-year-old killer had also completed a marksmanship course at school, DailyMail.com can reveal.

Former friend Joshua Charo, 17, of Parkland, Florida, said Cruz had taken shooting instruction as part of his JROTC program - and often pestered classmates for advice on gun purchases.

Charo said Cruz would send him photos of guns and other weaponry via Instagram and Snapchat but stopped after he was expelled from Marjory Stoneman Douglas High School last winter.

This image of Cruz wearing a Make America Great Again cap was used as his profile image on Instagram

He also told DailyMail.com that the killer was kicked out of school due to 'behavior issues' and because he was found to be carrying bullet casings in his bag.

'I knew him from freshman year to sophomore year,' Charo said. 'When we were inside of class, we would talk but when we were outside it, we wouldn't really hold a conversation.

'He usually liked to talk about hunting, guns, stuff like that - that particular subject.

'He always showed people the guns he wanted to buy and he would always ask if they had any suggestions for which guns they thought would be better and stuff like that.'

Charo added: 'He was studying marksmanship in JROTC [U.S. Army Junior Reserve Officers' Training Corps].

According to the JROTC website, the 10-lesson course, which is taught using air rifles, covers the history of marksmanship, as well as firearm safety.

Other subjects studied include aiming and firing and sight adjustment, with students given the opportunity to take part in competitions on completing the course.

Charo, who described Cruz as 'a bit odd', also said the slightly-built 5ft 7in killer found making friends difficult and was unable to get a girlfriend.

Florida gunman Nikolas Cruz, 19, was trained to use weapons and had taken a marksmanship course with the US Army Junior Reserve Officers' Training Corps, a former friend has revealed

This photo of a gun being held, as well as more weapons being stored in the closet, was posted on Cruz's Instagram page

Cruz also posted this photo on Instagram of a box of military grade bullets

Cruz's former classmate said clashes with peers were not uncommon. The killer allegedly had trouble making friends and was unable to get a girlfriend

Clashes with classmates were not uncommon, including one incident in which he fought with a boy named Amiyah because Cruz felt 'he was bothering him'.

After being expelled in early 2017, he reportedly enrolled in evening classes, but also worked for at least six months at a Dollar Tree store in Coral Springs.

Joshua Charo (pictured) 17, of Parkland, Florida, said he knew Cruz for two years in high school and described him as 'odd'

Staff at the store confirmed he had worked there but said they could not comment on their former colleague when approached by DailyMail.com.

Charo said it was there that he last saw Cruz, when he dropped by after watching a movie at a nearby cinema.

He told DailyMail.com Cruz had 'been like he always is' during the chance encounter last summer but had seemed uninterested in reconnecting with high school friends.

'I'm not sure he talked to anyone in Douglas after he was expelled,' he said. 'I'm pretty sure he didn't talk to anyone after that – I guess they kind of forgot about him, you know.'

Broward County Sheriff Scott Israel revealed late on Thursday that Cruz had confessed to carrying out one of the nation's deadliest school shootings and carried extra ammunition in his backpack.

Cruz told investigators he brought more loaded magazines to the school and kept them in the backpack until he got on campus.

The gunman fired into five classrooms - four on the first floor of the school and one on the second floor. The shooting lasted for three minutes.

Nikolas Cruz pictured as a baby, with his mother Lynda Cruz, who died last year

The Cruz family, comprised of the shooter, Lynda, and his younger brother Zachary, had previously occupied a large home (pictured) on a quiet road in Parkland until January 2017

After being expelled in early 2017, Cruz worked for at least six months at a Dollar Tree store in Coral Springs. Staff at the store confirmed he had worked there but said they could not comment

When he was done firing, the assailant went to the third floor and dropped his AR-15 rifle and the backpack containing the ammunition.

He then ran out of the building and attempted to blend in with fleeing students.

After the rampage, the suspect headed to a Wal-Mart and bought a drink at a Subway restaurant before walking to a McDonald's. He was taken into custody about 40 minutes after leaving the McDonald's.

Cruz was arrested nearby - just over two miles away from his workplace and close to the Coral Springs home he had been living in since the death of his mother Lynda in November last year.

The Cruz family, comprised Nikolas, his mother Lynda, and his younger brother Zachary, had previously occupied a large home on a quiet road in Parkland until January 2017.

Neighbors there told DailyMail.com that they were relieved when the family moved out, due to Cruz's strange behavior - and Lynda's.

One, who asked not to be named but rolled her eyes on hearing Cruz's name, said: 'He was weird. There was a lot of history there, a lot of stuff that went on.

'Take a closer look at his past, that's all I'm saying. Look at the mother too – there's a lot there.'

Nikolas Cruz, 19, was arrested after he stormed Marjory Stoneman Douglas High School in Parkland on Wednesday afternoon armed with an assault rifle

Authorities inspect the AR-15 rifle the teen gunman used in the mass shooting on Wednesday

Another video showed students literally shaking with fear as heavily armed police entered their classrooms and ordered them to put their hands up

Charo says despite reportedly being close to Lynda, Cruz never spoke about either his mother or his younger brother.

'He never mentioned his family,' he told DailyMail.com. 'I just found out yesterday he had a younger brother.

'I actually didn't know he was adopted. I didn't know much about his family – he never spoke about them at all, never mentioned them.

'It was a bit strange but then not a lot of teenagers talk about their families or anything like that.'

Other neighbors revealed they were terrified of the teen, who would 'bang his head on concrete' if he didn't get his way and was seen, on more than one occasion, trying to kill their animals.

'He could have killed any of us,' said Christine Roxburgh, who said that Cruz was also a peeping Tom.

She's once caught him peeking in her window.

'I said, 'What are you doing here?' He said he was looking for golf balls. I said, 'This isn't the golf course,'' she said.

Her husband Malcolm Roxburgh said the teen disliked pigs kept by another family and 'sent over his dog...to try to attack them', while another neighbor, Shelby Speno says she witnessed Cruz shooting at chickens owned by another resident.

'Lynda the mom was always apologetic. She had her hands full,' Shelby said.

The atrocity on Wednesday left 14 students dead, along with a football coach who also worked as a security guard, a senior who planned to attend Lynn University and an athletic director who was active in his Roman Catholic church.

The last of the bodies were removed from the high school Thursday after authorities analyzed the crime scene. Thirteen wounded survivors were still hospitalized, including two in critical condition.

Cruz was ordered held without bond at a brief court hearing on Thursday.

Florida gunman Nikolas Cruz's arrest affidavit The complaint affidavit against Nikolas Jacob Cruz reveals he has been charged with 17 counts of pre-meditated murder and confirms both of his parents are dead. The documents say that at 2.23pm on February 14, multiple 911 calls were received of a shooting taking place at the Marjory Stoneman Douglas High School. Cruz's height is give as 5'87, his weight as 128 lbs and birthplace United States of America. The affidavit outlines the chain of events that happened during the Marjory Stoneham Douglas High School massacre According to the document, Cruz was first spotted by an unnamed witness after arriving by Uber Both of Cruz's parents are deceased and he is living with a family, who give him his own room The affidavit states that Cruz admitted being the shooter and that he planned to blend in with crowd after carrying out the killings Cruz was charged with a total of 17 counts of premeditated murder relating to the shootings Cruz made his first court appearance accompanied by a public defender 'Multiple deceased persons were observed at the scene,' read the affidavit, which continues that 'the shooter attempted to blend in with fleeing students and was able to elude arriving officers'. A sworn statement from a witness, whose name was redacted, said he recognized Cruz as a 'troubled former student' who arrived in a 'small goldish colored vehicle' The witness stated Cruz was wearing a maroon shirt, black pants and a black hat and was carrying a black duffel bag and black backpack. He was walking 'purposefully' towards school buildings the witness said. 'Within a minute he heard gunshots and called a "Code Red" indicating an emergency on campus,' the affidavit reads. According to the affidavit, both Cruz's parents are deceased and he was staying with a family who have given him his own room in their house. 'Cruz stated that he was the gunman and entered the school campus armed with an AR-15 and began shooting students that he saw on the hallways and on the school grounds'. 'Cruz admitted that as students began to flee on foot he decided to plan to discard the AR-15 and vest with additional magazines so he could blend in with the crowd.' Advertisement

He wore an orange jumpsuit with his hands cuffed at his waist

After the hearing, Cruz's defense team revealed that he was on suicide watch and that he understood the magnitude of his actions.

Public defender, Melisa McNeill told reporters gathered outside the courtroom that her client was remorseful.

'He's sad. He's mournful. He's remorseful. He is fully aware of what is going on, and he's just a broken human being,' she said.

Another member of the defense team, Gordon Weeks, was brought to tears as he addressed reporters, telling them that Cruz 'recognizes' what he has done and is 'deeply sad'.

As the criminal case began to take shape, President Donald Trump, in an address to the nation, promised to 'tackle the difficult issue of mental health,' but avoided any mention of guns.

Trump, who owns a private club in Palm Beach, about 40 miles from Parkland, said he planned to visit the grieving community.

He weighed in on Twitter early Thursday, calling the suspect 'mentally disturbed' and stressing that it was important to 'report such instances to authorities, again and again!'

Soon after, a devastated mother of one of the 14-year-old girls killed in the shooting unleashed on Trump during a live TV interview, screaming for him to do something to prevent another massacre.

'President Trump, please do something! Do something. Action! We need it now! These kids need safety now,' a grieving Lori Alhadeff begged during a live CNN broadcast on Thursday.

As tears streamed down her face, Alhadeff told of how her daughter Alyssa was among the 17 shot dead.

Lori Alhadeff, whose 14-year-old daughter Alyssa was killed in the Florida high shooting, unleashed on President Trump on Thursday, screaming for him to prevent another massacre

Staff and students walked single file outside the school as they evacuated after the shooting

She glared into the cameras as she furiously demanded answers and urged Trump to take action on gun control.

'How do we allow a gunman to come into our children's school? How do they get through security? What security is there?' she yelled.

'The gunman - a crazy person - just walks right into the school, knocks down the window of my child's door and starts shooting. Shooting her! And killing her!

'I just spent the last two hours putting together the burial arrangements for my daughter's funeral, who is 14.

'President Trump, you say what can you do? You can stop the guns from getting into these children's hands. What can you do? You can do a lot! This is not fair to our families and our children to go to school and have to get killed!'

Angry students have also taken to social media threatening to boycott Trump's visit and they demanded the President do more than just offer 'prayers and condolences'.

Thousands gathered for a tearful, candlelit vigil held for the victims and their families on Thursday evening. On stage at the town's amphitheater were 17 four-foot-tall ornamental angels - one for each victim - lent to Parkland by Sunrise, Florida, where they were first used to honor the victims of the Sandy Hook Elementary School massacre.

An official GoFundMe account has been set up to raise money to 'provide relief and financial support to the victims and families of the horrific shooting.'