The university put out a series of alerts after 10:00 am (1500 GMT) ultimately ordering staff and students to “shelter in place,” as teams of police scoured the sprawling campus in New Haven, Connecticut.
But as the day wore on, there were no reports of shots being fired nor of any injuries. Nor was the presumed gunman found.
New Haven police announced later that they believed the call was a hoax, US media reported. The university is on recess for the Thanksgiving holiday until next Monday.
Officers said the tip off was made by an anonymous male caller from a pay phone, claiming that his roommate was en route to campus with the intention of shooting people.
At 1:45 pm Yale announced on its website that police would be conducting room-to-room searches, before partially lifting the closure at 3:10 pm and fully ending it at 4:40 pm.
Yale has more than 14,000 students and a teaching staff of more than 9,000. It was established in the early 18th century and is one of the top universities in the prestigious US Ivy League.