An incident management team is on scene examining the area around the crane, which remains in the water, Nagle said.
"We have received report of the sheen but we don't know how much it is," he said.
The San Francisco Fire Department received a call at about 10 a.m. that the crane had fallen onto its side and into the water, spokeswoman Mindy Talmadge said.
A man operating the crane was tossed into the water during the accident, but a nearby tugboat scooped him out immediately afterward, according to Nagle.
The man was transported to San Francisco General Hospital as a precaution, Talmadge said, as firefighters reported that the man seemed unharmed. It is unknown how long the man was in the water before being rescued, she said.
The Division of Occupational Safety and Health, known as Cal/OSHA, will investigate the accident to determine if the company in charge of the crane was using proper safety procedures before the accident occurs, Talmadge said.
