The University of Michigan said Saturday’s emergency alert may have stemmed from the sound of popping balloons on campus. At 4:35 p.m. on Saturday, March 16, the University of Michigan Division of Public Safety and Security (DPSS) and local law enforcement received about 20 calls reporting shots fired on the second floor of Mason Hall on the Ann Arbor campus. During these reports, a vigil was being held for those killed in the mosque attacks in New Zealand.