It was supposed to be a carefree summer getaway at a waterfront home on the Eastern Shore - a time for bonding with old friends while celebrating a budding romance. There would be boating, tubing and a bounty of steamed Maryland crabs.

But what began as a postcard-perfect trip for a group of college friends and siblings turned tragic in the early hours of Saturday when a fire roared through the sprawling house, cutting short three of the seven young lives.

Margaret Rose "Maggie" Fitzgerald, president of her 2007 high school graduating class at Saints Peter and Paul High School in Easton, and her brother Kennedy Fitzgerald, an honor student at the University of Maryland, College Park, died at their family's home, friends said yesterday.

Kennedy Fitzgerald's girlfriend and classmate at College Park, Christine Renee Maier, 19, also was killed in the blaze.

One of the Fitzgeralds' three siblings - a 15-year-old sister - and three friends escaped.

"Christine wouldn't want me to cry - she never cried, she was just such a happy person who always kept her chin up," said Rosemary Sharpe, 21, a friend of Maier's who made it out of the burning house.

"I don't know why I didn't die, but I just know I have to go on. It's just the worst thing I could possibly imagine."

Fire investigators were sifting through the charred remains of the 6,600-square-foot home on the Miles River. Deputy State Fire Marshal Joseph G. Zurolo Jr. said yesterday that they hadn't determined the cause of the fire.

Zurolo did not dispute relatives' identification of the three young victims, but he said a formal identification would not be made until the state medical examiner completes autopsies. The bodies were "burned beyond recognition," he said.

At the Fitzgeralds' home on Arcadia Shores Circle yesterday, family friends dug through rubble looking for photographs and mementos, against the grinding racket of backhoes renovating a house two doors down.

A sign with the burned-out home's name - "Gratitude on the Miles" - was surrounded by more than a dozen bouquets, one with a card vowing: "You will never be forgotten."

The recently constructed waterfront home was equipped with functioning smoke detectors, but not with an internal sprinkler system, Zurolo said. Residential sprinklers are not required in single-family homes in that area, he said.

The weekend gathering 70 miles southeast of Baltimore was centered around the new couple, who met in June during a summer class camping trip to West Virginia, friends said.

Maier invited Sharpe and Ashley McNerney, 21, to join her on her visit to the Fitzgerald home. The trio has been inseparable since middle school in Rockville, said Sharpe, adding that Maier was always planning entertaining getaways, including a trip earlier this summer to New York to celebrate Sharpe's 21st birthday.

Kennedy Fitzgerald invited a friend from Annapolis, Tyler Graf, 20, to come out for the weekend.

Parents Matthew and Margaret Fitzgerald, who moved into the new home earlier this year, were visiting relatives in New Jersey, said Devin Maier, Christine Maier's brother.

Friday evening, group members returned home exhausted from a day of tubing and boating. Sharpe, McNerney, Graf and the 15-year-old Fitzgerald sister headed upstairs to sleep.

Kennedy Fitzgerald and Christine Maier stayed up to watch a movie. About 1:30 a.m., Maggie Fitzgerald returned home from a concert, said Devin Maier.

Then, at 2 a.m. McNerney awoke to the whine of a smoke detector.

"I thought it was a mistake, but when I opened the door to the bedroom, I saw smoke and flames everywhere," she said. "We started screaming for Christine, but the smoke was so horrible and toxic, it was impossible to get across the hall."

McNerney and Sharpe woke up Graf and the younger Fitzgerald girl, who quickly escaped the burning house. But the pair panicked before realizing that they, too, needed to flee. They called 911 from a landing outside the second-story bedroom window, then jumped.

"We just ran," said Sharpe. "We saw the house burning and we knew there was no way Christine could still be in there. We knew she had escaped. She was so resourceful, she could get out of any situation."

More than 50 firefighters, volunteer and full time, from at least three counties spent nearly an hour getting the blaze under control, Zurolo said.

Maier was the outgoing geography major, whose love for adventure was sparked as a child, when she used to fall asleep reading atlases, according to her father, Patrick Maier of Federal Hill. Growing up in Montgomery County, the youngest of six siblings played rugby, loved animals and dreamed of a career working for National Geographic, the Travel Channel or even the Peace Corps, said her friends.

"She had a love of being in the world and taking advantage of every moment," Patrick Maier said.

Kennedy Fitzgerald was the sharp, environmentally conscious all-around guy, who made a great first impression on Maier's father. The Easton High School graduate was studying environmental science and policy in a university honors program and held down two jobs this summer - at a marina and at a biology lab.

"He was a really beautiful young man, very accomplished," Patrick Maier said. "I found him to be engaging and funny, and it was clear that he and Christine were very smitten with each other."

They shared a passion for adventure and loved the outdoors, said Devin Maier.

"They were inseparable," he said. "It was the end of the summer and they wanted to soak up every last drop of it."

Yesterday morning at Saints Peter and Paul High School in Easton, more than 100 friends of Maggie Fitzgerald crowded a hallway outside guidance counselor Debbie McQuaid's office. The bright student died weeks shy of her freshman year at the University of Massachusetts at Amherst.

The mourners spent hours scribbling in four leather-bound journals at the Catholic school. "I know heaven is real and you're there right now," one wrote.

They tacked up photos of a broadly smiling Maggie on a memorial bulletin board adorned with flowers and butterflies and filled three photo albums with memories of her - Maggie in a glimmering champagne-colored prom dress, Maggie cuddling with friends at a sleepover, Maggie in a white graduation cap and gown.

"There's that smile, everywhere, that infectious smile," said McQuaid, whose son graduated with Maggie three months ago. "She had such a zest for life. I always told people she was going to rule the world."

The Fitzgeralds are prominent members of Saints Peter and Paul parish, McQuaid said. Three of the family's five children attended the church's school.

So, it was not surprising that news of the Fitzgeralds' loss ground the school's schedule to a halt yesterday. A faculty retreat to gear teachers up for a new school year was canceled. Staffers cried and counseled each other and students, who wandered, dazed, into their rooms. They talked of starting collections for the family.

"No one has come to grips with this yet," said Principal James E. Nemeth. "She was such a strong force in this school, it's hard to fathom she's gone."