By Ralph Ellis and Laura Diaz-Zuniga

CNN

(CNN) -- The last known sighting of University of Illinois graduate student Yingying Zhang was on the afternoon of June 9.

The school released security camera footage showing the visiting 26-year-old Chinese scholar getting into the passenger side of a black Saturn Astra hatchback.

The FBI announced on Tuesday it had found the Saturn. The whereabouts of Zhang, however, remain a mystery.

A walk and concert in support of Zhang is scheduled for Thursday night at the school's Krannert Center for the Performing Arts. The event aims to show community support for her and give those frustrated by her disappearance a way to do something positive, said U of I senior Robin Huang, vice president of the Chinese Students and Scholars Association, which is organizing the event.

Case sends shockwaves through China

Zhang is one of more than 300,000 Chinese students and scholars attending US universities. Her disappearance has triggered widespread concern in China, with discussion of the case dominating both social and traditional media.

She had a year-long position at the university's department of nature resources and environmental sciences. She graduated from Beijing's prestigious Peking University last year with a master's degree in environmental engineering, according to a department webpage.

"She was about six weeks into her appointment as a scholar in the Department of Natural Resources and Environmental Sciences when she disappeared," said University of Illinois spokeswoman Robin Kaler.

The FBI is treating the disappearance as a kidnapping, but the campus police, in a recently released update, say they are calling it a missing persons case.

"While we categorize this as a missing person case, the FBI may use different terminology to categorize its investigations, and kidnapping is one possibility of many that we are pursuing," a statement said. "At this point in the investigation, there is no way to confirm exactly what happened, and we are not ruling anything out."

She talked to driver

Authorities would not say where it was or to whom the vehicle belongs and few details have been released about the search since it began.

University police said Zhang had just gotten off a public bus before the four-door hatchback approached her on the north end of the university campus.

Zhang can be seen standing by a tree as a black Saturn Astra pulls up next to her. She had a brief conversation with the driver before entering the vehicle.

The FBI says the vehicle appeared to be driven by a white male who circled the area before making contact with Zhang.

Zhang is 5-foot-4 and weighs 110 pounds, according to the FBI. She was last seen wearing a charcoal-colored baseball cap, a pink and white top, jeans and white tennis shoes. She carried a black backpack.

Her father arrives

Police have begged for patience from concerned students.

"We realize that this has been a source of anxiety for our entire campus community," campus Police Chief Jeff Christensen said in a message to the town. "Our concern for Yingying grows with each day that passes ... while we cannot share specific details on the investigation in order to maintain its integrity and direction, we continue to make progress in our search, and we will not give up until we find her."

Police say they are searching security camera footage, local hospitals, working with rideshare programs like Uber and Lyft, and checking other records.

Zhang's father, Zhang Ronggao, traveled from Nanping, China, to do what he could to help find his daughter, the Tribune reported.

The Chinese Students and Scholars Association plans to hold a walk and concert Thursday to show their concern for Zhang.

Concern in China

The number of Chinese students in the US has more than tripled since 2008 to 329,000 last year.

Urbana-Champaign is one of the most popular universities for Chinese students, with more than 5,600 students, who make up a sizable community both on campus and in the small town of 207,000.

According to Chinese state media, the school is favored for both its educational record and its safety -- with a bustling campus located around 150 miles south of Chicago in the agricultural center of Illinois.

Zhang's disappearance has attracted considerable attention back home, with groups set up on messaging app WeChat to share information about the case, which is also trending on Chinese social media.

A crowdfunding campaign set up "to assist the family of missing U of I scholar Yingying Zhang with expenses incurred as the search for her continues," has raised more than three times its $30,000 goal, with many donors leaving messages of support in Chinese.

Rewards offered for information

Zhang's family has teamed up with Champaign County Crime Stoppers to offer a $40,000 reward for information leading to an arrest in her disappearance.

"This is the largest award Crime Stoppers has ever granted since our inception," said Champaign County Crime Stoppers President John Hecker.

"We've been in the business, if you will, for more than 30 years. And I think that underscores the importance of how we are looking upon this particular case."

The FBI is also offering a $10,000 reward for information leading to the location of the missing woman.

CNN's Carma Hassan, James Griffiths and Steve George contributed to this report.