It was the first time Johnathan L. Fuller, a Navy boatswain's mate, had seen his sister in nearly 11 years.

Fuller, 22, whose family lives in Murray, Utah, came to Arlington, Texas, this week for a reunion with the sister, Monica Kaatz. They had been adopted by different families in 1978. On Thursday night, the two went to a roller-skating rink in Grand Prairie, a Dallas suburb, to celebrate Kaatz's 21st birthday.Early Friday - the morning of her birthday - they became trapped in Fuller's car as it slid off a flooded road into the swollen waters of Cottonwood Creek.

Kaatz and a friend, Kim Bumpus, 23, escaped out the car's side windows and saved themselves from the raging floodwaters by climbing a tree.

Fuller didn't escape. He died within seconds, officials said.

Police and fire crews performed several rescues early Friday morning as flash floods hit Grand Prairie, flooding homes in the northwest part of the city and stalling numerous cars as Cottonwood Creek overflowed, said Lt. Montie Gatlin of the Grand Prairie Police Department.

Nobody's story was more tragic than Fuller's.

In 1978, he and Kaatz were adopted from an orphanage in Costa Rica by separate families. She went to live with Larry and Pam Kaatz of Arlington, Texas, while he left with a family who now lives in Utah.

Right out of high school, Fuller joined the Navy to embark on what he hoped would be a long career.

Four years in the Navy earned him a spot on the USS Horne, a 500-man guided-missile cruiser operating out of the naval air station in Long Beach, Calif. As a boatswain's mate, he helped supervise the maintenance of the cruiser's metal structure.

Now, he was getting ready to re-enlist. "He was talking about trying to get into one of their schools in robotics," said Larry Kaatz. "He was interested in that area . . . He thought that was the direction in which electronics would be headed."

Over the past few years, the brother and sister began writing and phoning each other again. For Kaatz's 21st birthday, Fuller made arrangements to go on leave and drive from Long Beach to Arlington to see his sister again.

"This was something Johnathan had been planning for a very long time," said Pam Kaatz.

On Wednesday, Fuller arrived in Arlington. He and his sister would have two days together.

Thursday night, the two went roller skating in Grand Prairie with Bumpus. As they drove home, at about 1 a.m. Friday, they ran into a row of stalled cars in the southbound lane of the 1000 block of South Great Southwest Parkway. Police said Fuller was attempting to turn the 1985 Ford EXP sports car around when floodwaters literally washed the car off the road and into the creek.

As the car turned over and began to sink, Kaatz and Bumpus escaped through a side window and caught onto a nearby tree.

"Monica said that when she left the window, she knew he was still in the car," said Kaatz. "She said he wasn't able to get the window down on his side."

Emergency crews recovered Fuller's body, still in his sports car, about an hour and a half later.

Kaatz spent the rest of her birthday at a friend's house, sheltered from the need to talk about her brother's death. "She's obviously very distraught," said Mrs. Kaatz. "You know, what anyone would be feeling, especially with the irony of this happening on her birthday."

Said Kaatz: "If you can imagine seeing a brother that she thought a lot of, that she had talked to a lot of times in the past, anticipating him coming, seeing him for two days and growing to like him all over again, and then seeing him die . . . it's just unreal."