PITTSBURGH, April 3 (Reuters) - After receiving 10 bomb threats in three weeks, the University of Pittsburgh offered a $50,000 reward on Tuesday for information leading to the capture of whoever is responsible.
Shortly after word of the reward was announced, an 11th threat was made, school authorities said.
"The inability to bring this succession of threats to a quick end obviously is a source of frustration for everyone whose life has been disrupted by them," the university Chancellor Mark Nordenberg said in a statement.
"But I can assure you that law enforcement professionals are doing everything they can to pursue all possible leads and ... we have offered a very substantial reward for information leading to the arrest and conviction of those responsible for these crimes," he said.
The tenth threat arrived shortly after 2 a.m. on Tuesday in text messages sent to Pittsburgh Post-Gazette reporters, prompting evacuation of the university's Litchfield Towers dormitory, school officials said.
Students were allowed to return about four hours later.
The bomb threats began on Feb. 13, when one was made against the university's Chevron Science Center, where the chemistry department is located.
Most recently, at mid-morning on Tuesday, a text message to reporters targeted the same science center.
Two threats on Monday came in an email and scrawled on a university bathroom wall, forcing evacuation of David Lawrence Hall, which The building contains classrooms, lecture halls and a large auditorium. Also evacuated was the Cathedral of Learning, a towering landmark at the heart of campus that houses administrative offices, classrooms, libraries and a restaurant.
Asked for details about the most recent threats, university spokesman John Adele said the information was confidential.
The threats have not been confined to the University of Pittsburgh. Point Park University in downtown Pittsburgh also received a bomb threat in recent weeks, authorities said. (Reporting by Matt Stroud. Editing By Ellen Wulfhorst and Christopher Wilson)