Father and son are arrested over explosion which launched shrapnel 100 yards away, leaving one person with 'wartime' injury and damaging nearby cars

A father and son were arrested after they allegedly set off an explosive in a suburban New Jersey neighborhood, throwing shrapnel the length of a football field in every direction.

Police say Thomas Kaiser, 60, and his 28-year-old son Erich, detonated the device during multiple outdoor block parties on Saturday in Manville, critically injuring one person and dealing extensive damage to houses and a car in the area.

Dayna Cammacho was one neighbor hosting a Fourth of July weekend party, when her home surveillance camera picked up the moment a man appeared to light something. 

He ran away once it started smoking and seconds later, it exploded, which sent metal pieces flying as far as 100 yards away, police said.

'There was a car parked on that corner right there, a Kia, that had damage to it,' Cammacho pointed out to NBC 4 New York. 'If that car wasn't there, it would have hit us at the table.'

One 34-year-old man wasn't as lucky as Cammacho and her guests.

Standing 200 feet away from the blast in a nearby park, the man was struck in the stomach with shrapnel.

'It was like a wartime injury, it was horrible,' said Cammacho. 'If they weren't there, he would have bled out in that field and died.' 

Nicholas Barras, 24, was a good Samaritan who happened to witness the man go down from the projectile that hit him.

Thankfully, the trained emergency technician had his trauma bag full of medical equipment.

'He was on the ground, laying down. He was awake and conscious,' Barras told CBS New York. 'You could see into his stomach, it was not a pretty sight.' 

Nurse Antoinette Johnson and her sister also stepped in to help the injured man, abandoning their god son's graduation party.

'My anxiety was definitely on a million,' Johnson said, talking about the incident. 'But it's pretty easy for me to spring into action...and I would help anyone.'

The victim's family say Barras and Johnson saved their relative's life and stabilized him before he was airlifted to the hospital.

Metal debris whizzed throughout the neighborhood, shooting through a woman's bathroom, bedroom and and then out the back of her house into the backyard.

A family also had their brand new car's back window completely shattered.  

Manville Police and the New Jersey State Police Bomb Squad arrived on the scene shortly after the explosion occurred at 8:15 pm.

Investigators said the father and son attempted to light of a signal cannon, something they described as 'a device designed to create a large boom and smoke cloud when ignited.'  

Sources inside the police department told NBC that this device allegedly possessed by the Kaisers malfunctioned, causing the shrapnel to get flung in every direction.

'They're not experts, they don't have permits for it,' said. 'What was supposed to be a fun night turned into a tragic night.'

Both Kaisers were each charged with one count of fourth degree aggravated assault, one count of third degree possession of an explosive device, among other crimes. 

Both men were released and are due to appear in Somerset County Superior Court.