FARGO, N.D. - A somber quiet replaced the usual energetic bustle of a college dormitory hallway Tuesday on the first day back after a holiday weekend. On the closed door of Room 406 in Sevrinson Hall, photographs of four North Dakota State students hung along with sheets of notebook paper that became a makeshift memorial.

"We only met for a month, but you were a ball of joy."

"Your laughter was contagious."

"I'll miss ya ... cya in heaven."

"It was a difficult day," hall director Darcie Ellertson said after four first-year students were killed in a crash on an icy, slushy stretch of Interstate 94 Monday afternoon five miles west of Alexandria. All four students were teenagers from Twin Cities suburbs and their deaths jolted family members and friends from Fargo to Prior Lake. Three of the students shared a Sevrinson suite.

One friend had been texting passenger Jordan Playle all day.

"I last heard from her at 2:56 p.m. and when I didn't hear from her after 3, I knew something was wrong," said Senja Lotter, Playle's best friend since fifth grade. "She was so upbeat when I talked to her, and then to hear nothing. I'm still waiting for her to text and call me back."

Lauren J. Peterson, 18, was driving back to college from Prior Lake in a 2005 Chevrolet Malibu with Playle, 19, of Elk River, Megan Sample, 18, of Rogers, and Danielle Renninger, 18, of Excelsior.

State Patrol crash reconstruction experts were beginning their forensic mapping Tuesday to determine how the vehicle crossed the median at 3 p.m. before it was struck by an eastbound SUV that was then rear-ended by a third vehicle.

"It happened in less than a second," said Kari Christensen, the driver of the third vehicle who called 911. "Things were flying, it was like a tornado. I could see one of the girls in the car. I told the dispatcher, 'I don't think that it looks good.'"

It wasn't until Christensen talked to a state trooper that she found out that four people were dead. "It just breaks my heart."

'Best kid in the world'

At his Elk River home, Robert Playle said his daughter, Jordan, "was the best kid in the world -- you couldn't have a better daughter."

He said on most weekend visits, Jordan was busy zipping around with friends, but last weekend was different. She came home Friday and spent the entire three days with her family, never leaving the house without them.

"It was just like God was preparing us for something," he said. "We had the whole weekend with her. She was happy and fun-loving."

All the NDSU victims were wearing seat belts. Two other people were killed in separate accidents in the Alexandria area, including a 13-year-old girl, as the State Patrol responded to nearly 200 crashes Monday and early Tuesday in one of the few winter storms of the season.

"Obviously, it was snowing and the roads were slippery and that can't be ignored," State Patrol Lt. Eric Roeske said. "If there were other factors, we'll try to determine those in the course of the investigation."

Kendra Durst, a NDSU freshman from Buffalo, Minn., was heading back to campus just a few miles behind the students who were killed.

"The roads didn't seem that bad when we were going through Alexandria at 3 o'clock," Durst said. "We drove by the accident and saw that little car, and we got a call about the kids not answering their cellphones. We already knew who it was."

A sunrise prayer service was scheduled for 7 a.m. Wednesday at the school's student center. Students are asking everyone to wear pink on Wednesday and purple on Thursday in remembrance. The American flag at Fargo City Hall was lowered Tuesday to half-staff in the memory of the four students.

"I don't believe I have ever been faced with this type of tragedy of this magnitude," said Prakash Mathew, NDSU's vice president of student affairs for more than 30 years. "My heart practically sank."

'Epitomized the best'

Playle and Sample both graduated from Rogers High School. Playle was on the honor roll and took college-credit courses during her senior year at a nearby community college. She also played on the girls tennis team. She was majoring in marketing at NDSU.

Sample belonged to a marketing club at Rogers and also was on the honor roll. In the most recent yearbook, she was voted "Best at Life," akin to being the most likely to succeed. At NDSU, she was majoring in retail merchandise and design.

Rogers High School Principal Roman Pierskalla said in a statement that "Jordan and Megan epitomized the best, not only as students, but more importantly as citizens of our community."

The school's grief counselors "will be available as long as they are needed," Pierskalla said.

At the nearby Broadway Pizza early Tuesday afternoon, where Sample once worked, employee Jill Cox described Sample as "a doll, a sweetheart, a free spirit. Just a really good kid."

Peterson graduated from Prior Lake High School. She was "an excellent student, a cheerleader and a very popular girl," said School District spokeswoman Kristi Mussman.

Renninger, a 2011 graduate of Minnetonka High School who was active in dance, also was a marketing major at NDSU.

"Every single day she had this energy about her," said Erik Sill, a teacher at Minnetonka her senior year. "Her peers loved to be around her."

Michelle Renninger said her daughter made the dean's list at NDSU and loved college life and her suite mates. "Now there is just one left in the suite," she said.

That roommate returned to her family in West Fargo after she "was given the care and support that she needed" from a resident assistant, the hall's director and a counselor assigned to her hall, Mathew said.

Just before midnight Sunday, Danielle Renninger entered her final tweet, "Last night in my bed" followed by "#sadness."

What followed on her Twitter account were scores of expressions of grief and disbelief from her friends. One of them responded to Renninger's final entry, writing: "little did we know. R.I.P. little munchkin."

Staff writer Jim Adams contributed to this report. richard.meryhew@startribune.com • 612-673-4425 pwalsh@startribune.com • 612-673-4482 plevy@startribune.com • 612-673-4419 curt.brown@startribune.com • 612-673-4767