Federal authorities are investigating whether a group of Washington area police officers took money to protect a high-stakes gambling ring frequented by some of the region's most powerful drug dealers over the past two years, according to internal police documents and law enforcement sources.

The officers include five veterans in Prince George's County, a District police official and a former D.C. Housing Authority officer. Two under investigation have been spotted on police surveillance outside gambling sites, including one providing security in tactical gear. Witnesses have alleged that others wore police uniforms and drove marked cruisers to gatherings. One was arrested in a police raid outside a game with a handgun.