Key West, Florida -- About 20 tar balls have washed ashore in Key West, the U.S. Coast Guard said Monday night.
They ranged in size from about three inches to about 8 inches.
They were found on beaches of the Fort Zachary Taylor and the adjacent Navy beach at Truman Annex.
The Coast Guard said they were recovered at a rate of about three tar balls an hour throughout the day. The heaviest concentration was found at high tide, shortly after noon.
Samples were collected and will be shipped to a lab for analysis to determine their exact source, the Coast Guard said.
"The Coast Guard and National Oceanic and Atmospheric Administration - Florida Keys National Marine Sanctuaries (NOAA-FKNMS) will conduct shoreline surveys beginning Tuesday morning," the coast guard said in a statement.
"Additionally, an aerial search utilizing a Coast Guard Helicopter with a trained pollution investigator on board will also be conducted Tuesday morning."
U.S. Coast Guard