PITTSBURGH — Many University of Pittsburgh students are frustrated and scared after two months of bomb threats but remain supportive of school officials and police for how they are handling the outbreak.

More threats came Friday, following reports the previous night of a written threat in a stairwell at the Cathedral of Learning, the landmark building at the center of campus. That’s where the first threat was delivered. Later threats targeted numerous buildings and arrived via anonymous e-mails, bounced through a series of computer servers to mask the original sender.

“A lot of people are really scared,” said student Christine Lama, 19. “Now it’s gotten really bad. Our exams are getting all messed up,” and many students are getting “G” grades signifying unfinished work because of extenuating circumstances.

But Lama said she was not worried about an actual bomb and feels the school is doing all it can to address the threats.

No bombs have been found and no injuries reported. Authorities say they have made progress in the investigation.

But they haven’t released any details. The school imposed new security measures last Sunday and is offering a $50,000 reward for information.

Denise Bigelow, 22, an information science major, said the large university of about 35,000 students and teachers presents a huge challenge for campus police.

“I feel like there’s not a whole lot they can do. The person doesn’t even have to have anything incriminating on them to make the threat,” she said, referring to reports of handwriting on walls and in bathrooms.

Mary Ellen O’Toole, a former senior criminal profiler for the FBI, told The Associated Press that the Pitt threats are “pretty unique” as far as the sheer number.

Several dozen threats targeting more than 80 campus buildings have been made since mid-February. She said the number also suggests the threats may be coming from more than one person.

“This is exactly the kind of behavior that could trigger a copycater,” she said.

O’Toole said that if most of the threats are from one person, his or her motives have probably changed over time.

With thousands of students being roused from dorms in early morning hours, she said, the perpetrator may have a sense of power, as in “Wow, look at me.”

Political science major Derrick Brown, 21, said that as the threats have continued, many teachers are reverting to online classes and exams.