Reports of gunfire in Princeton’s historic Nassau Hall on Tuesday forced a campus-wide lockdown as university and local police officers combed the building for the source of the disturbance.

The cause of the noise turned out to be a construction worker using a hammer and chisel to repair a Nassau door according to The Daily Princetonian.

Initial reports of gunshots started around 7:55 pm. Twenty minutes after the door had been fixed, the first call to the University’s Department of Public Safety was made. Between 9:13 and 9:20, police formed a close-in perimeter Nassau and Public Safety officials are stationed around a wider area. Helicopters were also seen overhead. An email alert sent out to all students and faculty with the subject, “Report of Gunshots in Nassau Hall,” advised to “Stay away from area. Updates to follow.” A voice mail sent to all student and faculty repeated earlier reports and gave similar caution.

The investigation is now closed.