Eleven passengers and 10 crew members on the ship who were showing symptoms would be tested, Gov. Gavin Newsom of California said. “That number may significantly understate” the scope of infection, he said, or “it may indeed be abundance of caution.”

Additionally, 62 people who had traveled at the same time as the man who died were expected to be tested for the virus, which is spreading worldwide and has led to 14 deaths in the United States.

Two black helicopters hovered over the ship on Thursday morning, in the style of a military operation, as officials in camouflage and orange suits lowered what appeared to be a cooler and other gear onto the ship. After testing, the kits will be flown back to a laboratory in Richmond, Calif., where the results could be available within “a few hours,” Mr. Newsom said.

Officials said that the results would likely not be announced until Friday. Bill Pearce, 54, said fellow passengers had been staying in good spirits and milling around the ship until Thursday afternoon, when the captain announced over loudspeakers that all passengers would be confined to their cabins.