(CNN) - A University of Utah senior missing for more than a week was last seen at a park where she met someone in a car, Salt Lake City police said.
Mackenzie Lueck, 23, arrived at Salt Lake City International Airport on June 17 after visiting family.
She then took a Lyft to Hatch Park in North Salt Lake, where she was last seen in the early-morning hours.
"Mackenzie was met at Hatch Park by an individual in a vehicle. The Lyft driver left Mackenzie at the park with that person and stated that Mackenzie did not appear to be in any type of distress," Assistant Police Chief Tim Doubt told reporters on Monday.
Doubt said detectives are canvassing the area around the park and are looking for video surveillance. He said police have not yet confirmed the make or model of the car or obtained a description of the person.
"To date the family and her friends have not heard from her," Doubt said. Police confirmed she missed a flight to Los Angeles on the morning of June 23. He said Lueck, who lives in an apartment in Salt Lake City, also missed a midterm exam.
"At this time there is no evidence that any harm has come to her. However because of the circumstances of the case we want to make sure that she is all right."
Police said Lyft and the Lyft driver have cooperated with the investigation. The Lyft driver confirmed the route Lueck took and said she met someone after she was dropped off.
Lyft said that the route had no irregularities and ended at the destination Lueck entered. The driver continued providing rides immediately after the ride ended, the company said.
"We recognize how scary this must be for those who know and love Ms. Lueck," Lyft said. "The safety of our community is fundamental to Lyft and we are actively assisting law enforcement with their investigation."
Authorities believe her phone has not been on since June 17. They haven't been able to find its location, police said.
Police said that sometimes missing people don't want to be reached. If that is the case, they ask Lueck to reach out to police to let them know if she is safe.
"Mackenzie, we are asking you to please reach out to either the Salt Lake City police department or a law enforcement agency where you are at. We want to make sure you are safe and we will respect your wishes," Doubt said.
Police have set up a tip line -- 801-799-4420.
"We are asking anyone with information to please contact us," Doubt said.
Friend and sorority sister Ashley Fine told CNN affiliate KSL that Lueck has missed exams.
"She's extremely dedicated. She would never miss her midterms or anything like that," Fine told the Salt Lake City TV station. "She hasn't been home. She didn't show up to work, or anything."
Lueck had been at a family funeral in California, and last texted her parents at 1 a.m. June 17 when she landed back in Salt Lake City, CNN affiliate KSTU said.
"Detectives have been working throughout the weekend & will continue to follow any/all leads," police said Sunday night. "We are aware of info being shared by her friends & others about this case."
CNN's Eric Levenson, Marlena Baldacci and Artemis Moshtaghian contributed to this report.
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