As students headed to final exams at the University of Pittsburgh this week, with many exhausted and frustrated by more than 100 bomb threats that have disrupted classes and emptied dorms, they were hoping there would be no further evacuations now that a group has announced its bomb threat campaign is over.

Calling itself the Threateners, the group claimed responsibility for dozens of bomb threats delivered by e-mail to Pittsburgh-area news outlets since March 30. Last weekend, in an open letter to the university’s chancellor, the group said it would stop if the university withdrew its $50,000 reward for information leading to the arrest of the people behind the threats.

In early April, on the advice of law enforcement officials, the university had refused to negotiate with what appears to be the same anonymous group, university officials said. However, on Saturday, the offer of a reward vanished from the university’s Web site.

Officials said no threats had been received since Saturday morning, offering respite during the final week of school. Bomb-sniffing dogs had been on the scene since Feb. 13, when the first threat was found scribbled on a wall in a women’s restroom in a chemistry building.