Metro officials said they are working with Los Angeles County sheriff's transit authorities to review surveillance footage taken from inside the bus to determine the identity of the masked passenger, who was accompanied by a woman, Metro spokesman Marc Littman said.
The Monday afternoon incident is being investigated as a possible terrorist threat because of the fear it incited, he said.
Los Angeles County Department of Public Health officials don't believe the rider has Ebola and believe the incident was a hoax, spokeswoman Sarah Kissell Garrett said.
The passenger, who vanished in the confusion, was wearing a mask when he and the woman entered the bus at Venice Boulevard and Hoover Street about 1:45 p.m., he said.
He and the woman remained on the bus -- Line 33, which travels along Venice Boulevard -- for several minutes before he announced that he had Ebola.
The passenger removed his mask, threw it on the bus floor and exited the vehicle with the woman at Venice and Western Avenue, Littman said.
Some passengers quickly exited the bus as the driver relayed the incident to bus officials.
He drove the bus to a Metro bus yard in downtown Los Angeles, where it was taken out of service.
"We are taking every precaution," Littman said.
The driver, Littman said, was taken to