(CNN) A 13-year-old boy who was attacked by a shark early Saturday is still in serious condition, downgraded from the critical condition he was in originally, according to Dr. Tim Fairbanks, chief of pediatric and trauma surgery at Rady Children's Hospital in San Diego.

The boy was attacked while diving for lobsters in waters off Encinitas, California, authorities said. Encinitas is about 25 miles north of San Diego.

The boy suffered traumatic injuries to his upper torso, Encinitas lifeguard Capt. Larry Giles said. The injury was very large and deep in his chest, Fairbanks said.

The attack happened before 7 a.m., about 150 to 200 yards from Beacon's Beach, Giles said.

Several people were in the water diving for lobsters, he said, because it was the opening of the season for catching the crustaceans. Three good Samaritans heard the boy's cries and helped bring him ashore using a kayak, Giles said. One of the rescuers was a lifeguard sergeant who was among those diving for lobsters.

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