WASHINGTON (AP) - Thousands of illegal immigrants have obtained driver's licenses in three states, federal authorities said Thursday, highlighting a security hole that the Sept. 11 hijackers exploited. Three employees of Florida's motor vehicles agency were among 52 people arrested in a bribery scam that put driver's licenses in the hands of at least 2,000 illegal immigrants, officials said. The case, announced Thursday, follows similar arrests in Michigan and Maryland over the past week. "With a valid driver's license, you establish an identity," said Michael Garcia, assistant secretary of the Homeland Security Department. "There's no way to identify whether that...