“Today someone sent an envelope packed with white powder to the show. I offered to test it, but they said ‘no,’“ Ferguson quipped during a studio taping of “The Late Late Show.”

The taping went on as scheduled after the show received a threatening letter sent to Ferguson. Police Det. Gus Villanueva declined to discuss the nature of the threat against the talk show host, saying only that it was sent from overseas.

Two people at CBS Television City, where the show is filmed, were temporarily held in isolation after being exposed to the powder around 3 p.m. They were released after a hazardous materials team screened the powder and found it to be benign.

FBI spokeswoman Laura Eimiller said the agency was working with police to find out who sent the letter.

The brief scare appeared to have rattled Ferguson’s nerves.

“I was going to come out and talk about the earthquake, but I can’t do that now,” he said about the magnitude 5.8 quake that struck the East Coast. “Because the earthquake only scared millions of people on the East Coast, but the white powder did something much worse. it scared me.”