This is the shocking moment that a 14-year-old carjacker brutally beats a terminally ill grandfather on his own driveway before speeding away.

In the attack, which happened on the morning of Wednesday, April 3, in San Jose, California, 72-year-old retired plumber Hector Estrada said the teenage suspect pulled a gun and demanded his keys.

He was unloading groceries from his car, which was parked on his driveway in Coldwater Drive when he was approached.

This is the shocking moment that a 14-year-old carjacker brutally beats a terminally ill 72-year-old grandfather on his own driveway in San Jose, California, before speeding away

The video, filmed on a security camera recently installed by Mr Estrada, shows the attacker already in the driver's seat, ABC News 7 reported.

Grandfather-of-six Mr Estrada then bravely tries to pull him out.

Mr Estrada, who is suffering from a terminal pulmonary illness, said he refused to hand over his keys and the thief then showed him his gun but he still refused.

'I said no way, I don’t care if you have a gun I am not going to give you my keys. So he reached and grabbed them,' he said.

The carjacker then got into the car and tried to drive away and that is when Mr Estrada bravely tried to stop him.

'I reached in and grabbed it and tried to pull him back. He punched me and broke my glasses and that is how I got all these cuts,' Mr Estrada said.

Mr Estrada, who is suffering from a terminal pulmonary illness, said he refused to hand over his keys and the thief then showed him his gun but he still refused. He punched me and broke my glasses,' Mr Estrada said. The carjacker then punched him in the head, leaving Mr Estrada bleeding and unable to see. The suspect then got back in the car and drove away

The suspect allegedly then crashed the car after he tried to drive through a red light and hit another car before fleeing. He was tracked down by officers and held on charges of carjacking, robbery, assault with a deadly weapon and elder abuse

He added: 'I started bleeding and then I couldn't see anymore so I just went around the car and said you are on camera and he said "I don't care"'

The attacker then got back into the car and drove away, but San Jose police said they had a report of a hit and run crash involving Mr Estrada's car just 10 minutes later.

The suspect allegedly tried to drive through a red light and hit another car before fleeing.

He was tracked down by officers that evening and he was held at Santa Clara County Juvenile Hall on charges of carjacking, robbery, assault with a deadly weapon and elder abuse.

Mr Estrada was later interviewed with the cuts to his face and nose. He described the attack that followed after he refused to hand over his keys.