Updated

Police investigating the disappearance of a University of Vermont student are focusing their investigation "in one direction," officials in charge of the case said Tuesday.

Burlington Police Chief Thomas Tremblay said FBI and Vermont National Guard joined the search Tuesday for Michelle Gardner-Quinn, 21, who was last seen early Saturday morning as she headed back to campus after a night of partying with friends downtown.

"We are progressing ... we're following a number of very helpful leads" that have pointed police "in one direction," Tremblay said, adding that police have interviewed Gardner-Quinn's friends and acquaintances. "We do not have any specific suspect in mind at this point in time but certainly, helpful leads that are furthering our investigation."

Police are focusing their investigation on a "person of interest," a man they say unsuccessfully tried to lure another woman into his car about 20 minutes before and three-quarters of a mile from where Gardner-Quinn was last seen.

That woman told police the man was about 6-foot, in his 20s, muscular with cropped blond hair, wearing a baseball cap and gray hooded sweatshirt, and reportedly driving a white hatchback, possibly a Subaru, Tremblay said.

"We are following some substantial leads, but we don't want the public to stop sending tips — we don't want people to think that we're focused in one particular place," Burlington Deputy Police Chief Mike Schirling told FOX News. "The widest net possible is being cast now so we're sure we take in every possible piece of information that may have value to us down the road."

Gardner-Quinn was reported missing Saturday after she failed to meet her parents for dinner during the university's parents' weekend.

"Just based on what we know about her from her friends and family, it's not like her not to at least call," Ray Nails of the Burlington police told FOX News. He added that not calling "is completely out of her character."

Gardner-Quinn's parents, meanwhile, made an impassioned plea to the public for any information on the whereabouts of their daughter.

"We desperately are looking for our daughter," said John-Charles Quinn, the missing woman's father. "We remain hopeful that we will find her and she will be returned to us safe and sound."

"If they know anything at all about where my daughter Michelle is today or where she might have been on Friday night, Saturday morning, they tell us instantly," Quinn said. "We also ask that you please keep Michelle in your thoughts and prayers today and always."

Police interviewed several students who were with Gardner-Quinn when she went out Friday night to celebrate a friend's 21st birthday at several downtown bars. She left the group about 2:15 a.m. to walk back up the hill toward campus, accompanied by a person her friends described as "a random guy," police said.

That was the last time anyone saw her.

Students helped post fliers Monday on campus and around town in the hope that someone might come forward with information. Police, meanwhile, widened their search beyond the city limits, where officers had canvassed neighborhoods looking for clues or information.

Police planned to hold a series of informational meetings with the city and campus communities Tuesday night to discuss the case and public safety concerns.

More than 50 law enforcement personnel were working the case, Tremblay said.

"They've taken this on as a major crusade, a major cause and it is amazing to understand and to see this happen and I'm so glad that in the six weeks that Michelle has been at the university that she had made such good friends," Quinn said.

Friends and fellow students held an evening vigil Tuesday night, organized by the campus women's center and held at a fountain on the college green.

Handmade signs were laid on the brick ledge surrounding the fountain as students, faculty members and friends stood somber and silent, holding candles in front of them. "I Am Scared," read one of the signs. "Somebody saw something. Spread the word. We want Michelle Back," read another.

"It's emotional," said Megan Behlendorf, 18, a freshman from Essex Junction. "It's emotional knowing that someone could just be gone, in one night."

Police described Gardner-Quinn as 5-foot-8, 135 pounds, with shoulder-length brown hair and a pierced nose. When last seen, she was wearing a gray coat, a green cardigan sweater and a light blue T-shirt, police said.

Police also warned students to travel in groups and to stay in well-lit areas, advising them to walk near the street and away from the shrub-side of the sidewalk.

FOXNews.com's Sara Bonisteel and the Associated Press contributed to this report.