PITTSBURGH - Four buildings were evacuated on the University of Pittsburgh's campus on Thursday after what officials called a general bomb threat.
Thursday's threats were aimed at the Cathedral of Learning, the Chevron Science building, the Frick Fine Arts building and Posvar Hall.
There have been 23 threats made on the campus over the past few weeks. Investigators said some of the threats have been emailed, while others were found written on bathroom stalls.
On Wednesday, police evacuated the Frick Fine Arts building, Victoria Hall and the music building just before 9:30 p.m.
A trio of threats earlier on Wednesday was reported at the Cathedral of Learning, Posvar Hall and Litchfield Tower C, police said.
Earlier Wednesday, a threat was reported at Thackeray Hall around 10:30 a.m.
University officials increased a reward for information about the wave of recent bomb threats on campus from $10,000 to $50,000.
Officials also said Wednesday that federal law enforcement is increasing its efforts to find whoever is responsible for the threats.
Authorities said they have traced the email threats through computers in Austria, but have not released any other details.
University of Pittsburgh Chancellor Mark Nordenberg sent a letter to the Pitt community Tuesday detailing the efforts being made to find whoever is responsible for the threats.
In the letter he said, “Those responsible for these threats not only lack basic respect for the thousands of people whose lives have been disrupted but must possess a heartless streak.”
Pitt student Erika Utter said she and other students are starting to worry.
“My parents are starting to feel unsafe about me being here,” Utter said.
“I personally have missed six classes in the last two weeks,” student Matt Rippon said. “I’m kind of curious as to whether or not they’re going to give us these classes back because I’m paying for an education and I’m not getting the full benefit of that education.”
Pitt spokesman Robert Hill said last week that the school is determined to bring to justice the person or persons responsible. He said there hasn't been a similar wave of threats since he came to the school in 1999.
"We're going to prosecute this individual to the fullest extent of the law, federally, the furthest we can possibly prosecute him,” said Chief Tim Delaney. “This is truly an inconvenience for the 99.9 percent of these good kids that are going to school and getting interrupted here. It has to be stopped."
University police, the FBI and the U.S. Secret Service said they have a person of interest in the investigation. Anyone with information about the threats is urged to contact the University of Pittsburgh Police Department.