Bloody clothing was found inside a science laboratory building where missing Yale student Annie Le was last seen, FOX News confirms.

Police sources said the clothing was found late Friday night above ceiling tiles in the basement of the five-story building where Le worked as a pharmacology graduate student. The items have not yet been linked to her disappearance by investigators.

The FBI said Saturday that only "potential evidence" has been seized in the search for Le, a 24-year-old pharmacology graduate student who disappeared days before she was scheduled to be married. Le was last seen Tuesday entering the lab building on 10 Amistad Street in New Haven, Conn.

Parts of the building have been labeled a crime scene, WTNH-TV reported Sunday.

"Items that could potentially be evidence have been seized. None have yet been associated with Annie Le,” FBI Special Agent Kim Mertz said while declining to confirm reports that the evidence included bloody clothing.

Mertz also told reporters Saturday evening that there was no truth to a report that a body had been found.

"We are not in a position to conclude whether this is a missing persons case or whether criminality is involved," Mertz said.

University officials have urged the public not to jump to conclusion.

"The investigation is at a very difficult stage," University Vice President and Secretary Linda Lorimer said, adding that many agencies are working together to find out what happened to the student.

She said Le's family, which has asked for privacy, doesn't think Le would simply run away.

Le was last seen about 10 a.m. Tuesday morning on surveillance camera outside a lab in the Yale School of Medicine complex, less than a mile from the main campus.

About the same time, she swiped her Yale ID at the facility's entrance. There was no footage of her leaving the building, in spite of a fire alarm that went off about 12:40 p.m. The alarm isn't thought to be connected to her disappearance.

Her purse, cell phone, credit cards and money were found in her office, a few blocks from the lab. She has not contacted her fiance, family or friends since Tuesday.

The New York Daily News, citing an unnamed police source, reported earlier Friday that detectives had questioned a Yale professor. Le, a doctoral student in pharmacology at the Ivy League university, was supposed to attend the professor's class Tuesday afternoon, but the course was canceled shortly before Le was reported missing, according to the Daily News.

But Lorimer told the Yale Daily News later that there was no reason to believe a professor is a suspect in the case.

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Meanwhile, the missing woman's family canceled her Sunday wedding on Long Island, N.Y., according to a supervisor at the hall where the ceremony and reception were to have taken place.

"The wedding is off," Nadeen Fotopoulos, a manager at the North Ritz Club in Syosset, told the News. She said 160 guests were supposed to attend.

"It's very sad," she told the paper. "The hall will be dark Sunday morning."

Detectives were spotted Saturday questioning a man outside the lab where Le worked. When they finished talking, the man got in the front seat of an unmarked car and one of the FBI agents got in the back seat. The car then drove away.

Authorities previously said they had no evidence to indicate foul play in Le's disappearance. More than 100 investigators are working on the case.

On Friday, Yale offered a $10,000 reward for information leading to the missing student. Investigators searched her office, the lab facilities where she did research and her apartment.

Investigators were examining security camera footage from some 75 cameras near the building where Le was last spotted.

"They are going frame by frame, looking at every image," Conroy said Friday.

Le, a California native, was to be married to Jonathan Widawsky, a graduate student in physics at Columbia University. The two met as undergraduates at the University of Rochester. Widawsky has been cooperating with the investigation and is not considered a suspect, authorities say.

Le is 4-foot-11, 90 pounds and of Asian descent with brown hair and brown eyes.

Anyone with information on Le’s whereabouts is asked to contact the Yale Police Department at (203) 432-4400.

Click here for more ont his story from the New Haven Register.

Click here for more on this story from the New York Daily News.

FOX News' Rick Leventhal and the Associated Press contributed to this report.