The father of a 10-year-old rescued from pounding surf off the California coast in a dramatic scene captured on video says he is beyond grateful to the teenage lifeguard who saved his son.

“He ran into that water despite those conditions that are deadly,” Sumit Rai told the Associated Press on Wednesday. “You have 10ft waves; you have riptides and currents coming in.

“It is not safe for him to go into that water. So he’s risking his own safety.”

Rai’s son Nathaniel was standing in shallow water when he lost his footing and was pulled into the ocean Saturday by powerful swells that suddenly came ashore at Seabright beach in Santa Cruz, about 60 miles (100 km) down the coast from San Francisco. Rai, who was in his home city of Dallas, said he heard about what happened when he spoke to his kids on the phone that evening.

“My son told me that he drowned and my son told me that he went unconscious,” he said. “He was very subdued, still in a state of shock.”

By the next morning, Rai had watched the video of the rescue that has since caught the attention of Donald Trump. The president posted on social media about awarding the lifeguard who saved Nathaniel, Ryder Williams, a “high civilian honor” – and inviting him and his family to the White House.

Williams, 16, said he saw the boy lose his footing in ankle-deep water. He radioed in and then raced toward Nathaniel.

“After the first wave, I was unable to pull him out because he was limp and the waves were pushing so hard,” he said in a statement.

California State Parks, which employs the lifeguards at that beach, said the boy was swept about 15 yards (13.7 meters) into the ocean before the lifeguard made contact with him.

In the video, Williams can be seen diving into a coming wave while holding tight to the boy.

Another lifeguard jumped in to help, along with some bystanders, who Williams said he warned to go back to the shore.

“I’m grateful to have had the opportunity to return the child to his family safely,” he said. “This is my job and I love what I do. I’m thankful to my fellow lifeguards who perform rescues just like this every day.”

Meanwhile, asked by the California Post if their family planned to accept the White House’s invitation, Williams’ father, Shane, has said they had not immediately heard from the Trump administration officially.

Nathaniel had no serious injuries. And after a medical evaluation, he was released to his family, the California State Parks said in an emailed statement.

Rai said his son told him that he got sand in his lungs and was coughing it out after getting to the shore. Now his son, who is expected back from California in a few days, is dealing with the psychological effects of what happened.

“He’s still been thinking about it a lot. It’s on his mind,” he said. “It bothers him when he’s sleeping. So it’s obviously traumatizing.”

Rai has reached out to Williams and said he hopes to be able to thank him directly.

“What he did, I can never ever repay,” he said. “I’m forever grateful.”

Guardian staff contributed reporting