The robbery was all captured on camera.
Eduardo Reyes says he received a message on OfferUp about the iPad he was looking to sell.
The meeting was recorded by the camera in his Tesla, from one suspect in a black hoodie pulling out a gun to another suspect joining the ensuing struggle.
"I turned around and the other kid had a gun out pointed at me and he was like 'give me your iPad!'"
Concerned about his wife he says he drew the two suspects' attention towards him by holding onto the iPad.
Reyes says at first he didn't believe their weapons were real.
"He fired the gun towards the sky and I grabbed one of the kid's hands. He had his gun out. I was trying to point it away from me."
Reyes says the suspect pistol-whipped him. When he told his wife to call 911 one of the suspects turned to attack her.
"The one I originally gave the iPad to he went after her and grabbed her leg and she fell to the ground while the other kid was attacking me."
In the end the two got away with Reyes' iPad and his wife's phone.
Reyes was treated at the hospital for several head wounds.
Pomona police are investigating - and have a warning for anyone using online apps to exchange goods.
"Look at their profile picture, make sure their phone number is legit, make sure you're meeting in a well-lit and public place," said Ally Mejia with the Pomona Police Department.
Reyes normally takes safety precautions. But he thought he was dealing with a kid, who said he was coming with his mother to meet Reyes.
"Definitely not doing that again."
He says he'll pick a safer place like in front of a police station in the future.
Anyone with information about this incident is asked to contact Pomona police.