Officials at Nichols School ordered the evacuation Monday afternoon of a building on the school's North Buffalo campus at 1250 Amherst St.
"Several students received a text threat shortly before dismissal was scheduled this afternoon," said Michael DeGeorge, Buffalo Police spokesman.
The evacuation of the Albright Building occurred around 3:30 p.m., said DeGeorge. The Buffalo police K-9 unit responded to the scene and conducted a sweep of the premises, said DeGeorge.
"Late the afternoon, police gave the all-clear sign," he said, noting that the investigation is ongoing.
Regular activities were resumed at the school by late afternoon, said Jesse Baier, director of marketing and communication at Nichols.