PORTLAND, Ore. (AP) — A number of federal buildings in Portland have been closed and the FBI is investigating after a car bomb threat was made. The FBI said in a statement Friday that investigators are working to determine whether the threat is credible. Two law enforcement officials spoke to The Associated Press on condition of anonymity because they weren’t authorized to discuss the investigation publicly. They said the threat was received Thursday and warned of the intention to use a car bomb to target federal property. Demonstrators have taken to the streets of Oregon’s largest city nightly since the May police killing of George Floyd. It wasn’t clear if the threat was related to the protests.