Investigators are trying to identify the prankster and will pursue criminal charges if they do, Riviello said.
He declined to provide additional details or confirm reports that the IP address used by the prankster has been traced to New York, saying the investigation continued.
John DiFava, chief of MIT's campus police, acknowledged the delay in telling students about a possible gunman on campus. "I have to look into it and find out the reason for the lag," he told the Boston Globe.
Junior Zach Wener-Fligner told the newspaper that the delay was "a little worrisome."
"But I assume the relevant area was locked down," he said.
About 11,000 people attend the prestigious school outside Boston where students are famous for their smarts as well as their stunts, including once putting a police car on top of a domed campus building.