Friends of a University of St. Thomas sophomore killed early Saturday in an intense, quick-burning house fire banded together in shock and grief Saturday evening to remember the laid-back baseball fan they called "Carson."

Michael Adam Larson, 20, of Woodbury, a sophomore at the Catholic college, died in the 3 a.m. fire at the house at 1795 Selby Av., where he lived with three friends. Three others who were in the house at the time of the fire -- two house mates and a girlfriend of one -- jumped from a second-story window to escape. They suffered smoke inhalation and minor injuries and were taken to Regions Hospital, said St. Paul Fire Marshal Steve Zaccard.

Carson, who was sleeping on the couch when the fire broke out, didn't make it out.

Flames were leaping from the two-story house when firefighters arrived at 3:15 a.m. They fought the fire on the first floor as they tried to rescue Larson, but he was dead by the time they entered.

The fire started on the home's enclosed porch, but an official cause has not been determined, although it's not believed to be suspicious in origin, Zaccard said. An autopsy is pending.

"We really don't know why he wasn't able to get out," Zaccard said. "He could have been overcome by smoke; he could have been disoriented. The fire blocked his access to the front door -- why he didn't go out another way, we don't know."

Doug Hennes, vice president for University and Governmental Relations at St. Thomas, said the five students were spending a quiet evening watching TV in the house, which is about six blocks east of campus. One went home, he said and the other four, including Larson, went to bed at about 1:45 a.m. Three went upstairs, while Larson stayed downstairs on the living room couch.

At about 3 a.m. the smoke alarm went off, waking the students upstairs, who didn't believe they could make it downstairs because of heavy smoke, Hennes said. So they jumped out the window but were not seriously injured.

The house sustained extensive fire, heat and smoke damage estimated at $120,000 to the building and $40,000 to the contents. It was not required to have a residential fire sprinkler system, Zaccard said, and no nearby homes were damaged.

It was the third fire fatality in St. Paul this year.

On Saturday afternoon, yellow tape surrounded the house, which was charred on the front and boarded up. The porch had collapsed. The front windows were boarded up, with the exception of broken windows on the side where the three students escaped.

St. Thomas students Tom Gallaher and Steve Stark, who live down the block, said they awoke to the sound of windows breaking just before firetrucks arrived. They didn't know Larson but were shaken.

"A student died; you don't want to see that," Stark said. "A 20-year-old -- one of us."

A prayer service for Larson was to be held Saturday night on campus.

Larson was studying mass communications, and had also focused on biology because of strong views about protecting animals and wildlife, said his best friend, Grace Vo. He switched to his current major because he wanted to be a sports analyst, she said.

The two, who previously had dated, had remained close friends. Vo said he loved video games and sports, particularly the Minnesota Twins. He gave Vo one of his most prized possessions -- a Homer Hanky from opening day at Target Field.

The two last communicated via text message on Friday night, Vo said. He asked if she had plans and if she would like to come over, but she didn't, she said.

"I woke up the next early morning to hear that he died," Vo said. "It's very unreal, tragic, and I feel I'm in denial about it."

Larson's friends took comfort in memories of his laid-back personality.

"He was just so happy," said Mariah Gruenke. "He already understood life; he knew it was a journey and he wasn't stressed out about all the things in school, all the drama. He was just happy, and it was great to know him."

A Facebook tribute page for Larson, called "Carson" by his friends, featured photos of a grinning, lanky young man sporting hockey jerseys and a Halloween costume.

On the page, his friends expressed disbelief and grief. Many had only seen him hours before the fire, yet didn't learn that he was gone until Saturday morning.

"You saved my life, Carson," wrote one house mate who escaped the fire. "I can't explain how much we all miss you."

"I'm so glad I got to know him; he truly is a friendly and very happy guy," Vo said.

Staff writer Tim Harlow contributed to this report. Abby Simons • 612-673-4921