Another wave of bomb threats at the University of Pittsburgh

(CBS/AP) The University of Pittsburgh is continuing to labor under a wave of bomb threats after a dozen more were made Thursday on campus.

After evacuating five dorms early Thursday, seven more were were made to various campus buildings, reports The Pitt News, the school's student newspaper. There have been 79 total threats this semester, according to the paper.

"We're pretty use to this; we've become accustomed to it," student Evan Kremmel told CBS affiliate KDKA in Pittsburgh. "It's just everyday protocol I suppose."

The threats began in mid-February, at first targeting a landmark building at the center of campus. But in recent weeks numerous buildings have been threatened.

Authorities have said they've made "significant progress" investigating the threats.

The Department of Justice says in a statement Wednesday that information from students and community members has helped authorities focus on potential suspects in the case.

The DOJ says that people with tips have many options for reporting and can remain anonymous. Pitt is offering a $50,000 reward for information.

Fifth-year chemistry student Brian Graham said the first threats were written on walls in buildings and he hoped security officers would catch the perpetrator. But, he said, threats then started arriving by email.

"I think it's a little bit more nerve-racking," Graham said of the latest wave of threats. "I have to either stay later or come in different hours. I would be about to leave home, and then there'd be a bomb threat."