Five men accused of setting fire to homes under construction in an upscale development outside Washington have been indicted on federal charges, prosecutors said Monday.

The Dec. 6 fires destroyed 10 houses and damaged 16 others in the Hunters Brooke (search) development. Damage was estimated at $10 million.

Interim U.S. Attorney Allen Loucks said a grand jury had indicted Aaron Speed (search), 21; Patrick Walsh, 20; Jeremy Parady, 20; Michael Everhart, 20; and Roy McCann, 22. All were charged with arson, conspiracy to commit arson, and aiding and abetting the arsons.

Loucks didn't rule out the possibility that other arrests could be made. The indictment alleges that the five suspects conspired with each other "and with other persons known and unknown to the grand jury."

His declaration included no information about the possible motives, including whether the fires were hate crimes.

Speed was a security guard at the development and Parady was a volunteer firefighter. Walsh has been described as the ringleader of the group, members of a street racing club known variously as the Family and the Unseen Cavaliers (search).

Investigators had said they believe the fires were set primarily to gain notoriety for the group although they have looked at other possible motives including revenge — Speed allegedly believed the company did not show concern after the death last year of his infant son. They also looked into race as a possible motive, since many of the families buying homes in the development are black while those arrested are white.

Loucks wouldn't comment on the status of a sixth suspect arrested last month, Michael Gilbert, or whether he is cooperating with investigators.

Just one of the houses was occupied at the time of the arsons; it was not significantly damaged and the family was able to return home by around mid-December.

Loucks announced the indictments hours after he was sworn in as interim prosecutor, taking the place of Thomas DiBiagio, who resigned last month to join a Washington law firm. Loucks has been an assistant U.S. attorney since 1994 and will serve as interim U.S. attorney for 120 days or until a replacement is found.