OCEANSIDE -- Friends and family gathered Thursday in Oceanside for a seaside memorial to celebrate the life of Lucas Ransom, the UC Santa Barbara student killed by a shark last week.

Some of the 150 people who turned out for the memorial paddled into the ocean to drop flowers and say prayers for the 19-year-old body boarder. Others released green balloons, with messages of love and support.

The water just south of the Oceanside Pier was picked for the memorial because it had special meaning to the Ransom family.

Ransom grew up in Riverside County and attended Perris High School. He was a junior studying chemical engineering student at UCSB.

Meantime -- the Santa Barbara County coroner's office Monday identified the shark that killed Ransom as a great white.

Shark Research Committee president Ralph Collier examined the bodyboard and determined that the teen was killed by a great white shark measuring 17 to 18 feet long and weighing 4,000 pounds.

Surf Beach, where the attack took place, reopened three days after the shark attack.

Ransom, who was on a bodyboard, cried out for help on Friday as a shark attacked him about 100 yards offshore.

His friend, Matthew Garcia, says he was only two feet from Ransom when the shark rose out of the water without warning.

"When the shark hit him, he just said, 'Help me, dude!' He knew what was going on," Garcia told the AP.

"It was really fast. You just saw a red wave and this water is blue - as blue as it could ever be - and it was just red, the whole wave. Even the barrel was red."

Garcia says he was pounded by waves as he looked for Ransom.

He finally spotted his boogie board, which was attached to Ransom by a cord, and swam to him.

Garcia says he did CPR as he pulled him from the water, but Ransom was limp.

"He was just floating in the water. I flipped him over on his back and underhooked his arms. I was pressing on his chest and doing rescue breathing in the water," Garcia said.

"He was just kind of lifeless, just dead weight."

Ransom suffered a massive wound to his left leg, the sheriff's department said in a statement.

Lucas and his brother Travis Ransom were both star swimmers for Perris High School.

During his senior year, Ransom qualified for the CIF in the 50 and 100 freestyle and the 100 breaststroke.

According to the Press Enterprise, Ransom was also among three lifeguards at the Cal Oaks Sports Park complex who pulled a drowning boy from a pool in 2007.

The three rescued the boy, cleared the pool and helped him regain consciousness before paramedics arrived.

All were honored by the city of Murrieta for their quick thinking and coolness under pressure.

Authorities could not immediately determine what kind of shark attacked Ransom.

Surf Beach is located north of Santa Barbara and west of Lompoc on Vandenberg Air Force Base.

Shark sightings reportedly are common off Surf Beach.

"Surfers like the area, especially on a day like today when the break is head high and smooth. But they say they see sharks," said Clay Garland, head ranger at Jalama Beach.

But attacks on humans are rare.

in 2004 while diving off the coast of Mendocino, north of San Francisco Bay.