ten minutes to leave. >> our protocol is to clear the building and move kids away. >> reporter: the scare, one of a number of threats that have disrupted classes throughout the country. in recent past weeks, the fbi responding to over 20 threats to historically black colleges and other institutions. the fbi saying it's identified at least five suspects after discovering the calls emanated from a fake phone number. >> thaets that are made based on race or motivated by race are totally unacceptable. >> reporter: authorities did not find any devices at dunbar or in the hbcu threats. but tonight, in this new case involving the vice president's husband, police say the threat did not appear directed at the second gentleman. and they say at this point, they have no reason to believe that it is tied to recent bomb threats against historically black colleges and universities. david? >> pierre, thank you. now to the scene playing out on the u.s./canada border tonight. the truck driver protests over vaccine mandates and covid restrictions. sparking a state of emergency in