Three Ivy League school campuses issued temporary evacuations Sunday afternoon after receiving bomb threats.
The incidents at Cornell, Columbia and Brown universities came two days after a similar threat took place at Yale University Friday.
The New York Police Department was called to Columbia's campus around 2:30 p.m. and students and visitors were told to avoid the area, the school said on Twitter. About two hours later, the school announced that the threats "were deemed not credible by the NYPD and the campus buildings have been cleared for reoccupancy."
Brown University's officials said in a statement that officers were called in after a bomb threat was made over the phone. Then, at around 5:45 p.m., the school announced that investigators found no evidence of a credible threat.
"Buildings that had been evacuated are now reopened, and university operations have resumed as normal," the school said in a statement.
Cornell University officials said a security perimeter was put into place around 4:10 p.m. as officers investigated the threats. Around 7:34, the school said there was no credible threat and reopened the campus.
"We are relieved to report that this threat appears to have been a hoax. A cruel hoax; but, thankfully, just a hoax," Cornell representatives said in a statement.
Police closed down Yale's campus and some local businesses for over four hours before they gave an all clear, ABC affiliate WTNH reported.
Police officers were still investigated the threats at Cornell and Brown Sunday evening.
Later Sunday night, the NYPD tweeted that the ordeal at Columbia was a "swatting incident," and they will continue to investigate.
No devices have been found at any of the schools and investigators have not made any arrests.
ABC News' Jason Volack and Darren Reynolds contributed to this report.