Researchers scrambled to clean up tar balls and puddles of oil from the beaches of Alabama's Dauphin Island, while a strip of oil about two miles long and three feet wide stretched along Petit Bois Island, about five miles away off Mississippi, Gov. Haley Barbour's office said.

It marked the first time oil has hit Mississippi's shores since the largest oil spill in U.S. history erupted in late April. And while tar balls associated with the Gulf spill had hit Dauphin Island, about 35 miles south of Mobile, in early May, residents said that June 1 was the first time they had seen oil hitting the beach.

Only part of the island's beaches have been lined with protective booms, with much of those barriers lined up near a protected wildlife area on the west end of the island.

The National Oceanographic and Atmospheric Administration had warned earlier this week that the spreading slick from an undersea BP oil well was heading toward the Alabama and Mississippi coasts.