In the hours after two bombs exploded near the finish line of the Boston Marathon, killing at least three and injuring more than 170, college administrators across the country frantically rushed to check the whereabouts of students and staff at the race. Several college newspapers kept running lists of participants and spectators with ties to their schools who had been safely located.

In Boston, which is packed with colleges, many schools upped their security and urged students to stay inside their residence halls and apartments Monday evening. They also encouraged students to seek counseling as they processed what had happened.

Emerson College and Berklee School of Music canceled classes on Tuesday. The University of Massachusetts Boston closed its campus for most of the day but planned to reopen at 4 p.m., according to its Web site.

Several colleges have reported that their students were injured in the blasts. A Boston University student was “critically injured,” according to a statement from its president. Seven Emerson students were treated for injuries and all have returned to campus, according to a note from its president posted online. Three Tufts University students who were watching the race received non-life threatening injuries, and three Northeastern University students were injured, according to the Boston Globe. Berklee officials received a report that one of their students was injured, although they had not made contact with him, according to a statement from the president posted online.

Harvard University had at least one staff member wounded in the attack, according to an e-mail President Drew Faust sent to the campus community on Tuesday.

“The Boston Marathon is an event that demands resilience,” Faust wrote. “As we struggle to make sense of yesterday’s events, I urge all of us to draw on the strength of the Harvard community and the support of colleagues and friends.”

Many school officials also urged their students to look out for their classmates and volunteer to help if they have the opportunity to do so. Tufts held prayer services late Monday and early Tuesday. North­eastern plans to hold a vigil Tuesday afternoon. Boston College — located at mile 21 of the marathon and about five miles from where the explosions occurred — has organized a Catholic ”Mass of Healing and Hope” for Tuesday evening.