PHOENIX, Oct 15 (Reuters) - The owners of a suburban Phoenix dog-boarding kennel and two caretakers, one of them the son of U.S. Senator Jeff Flake, were indicted on animal cruelty charges on Wednesday after the deaths of 21 dogs at the facility in June, county prosecutors said.

A state grand jury indicted kennel owners Jesse Todd Hughes and Maleisia Hughes each with 22 felony and seven misdemeanor counts of cruelty to animals and one count of fraud for the incident inside a cramped room at the Green Acre boarding facility, prosecutors said.

Authorities said the dogs died from suffocation and overheating.

Caretakers Logan Flake and Austin Flake, son of Senator Flake of Arizona, were each charged with 21 felony and seven misdemeanor animal cruelty charges, according to the indictment.

"We now look forward to the next step in seeing that justice is served in this case," Maricopa County Attorney Bill Montgomery, who has come under fire from the dog owners for taking too long in filing charges, said in a statement.

The four defendants could not immediately be reached for comment.

"This is simply the next step in the legal process, and I have confidence in that process," Senator Flake said in a brief statement.

Sheriff's investigators said the dogs died while the owners were in Florida and left the Flakes to care for them. Some of the dog owners were initially told their pets had run away.

The caretakers told authorities that they discovered a power outage in the room where the dogs were housed when they went to check on the canines. It was unclear how long the power had been off.

A preliminary investigation showed a hole scratched out of the drywall in a boarding area, which had exposed some electrical wires. These looked like they had been chewed through in places.

A group of the dog owners have filed a civil lawsuit against the Hughes and the Flakes, accusing them of fraud and neglect.

The lawsuit in county Superior Court alleged that the dogs were confined in cramped quarters and faced "neglect, mistreatment, physical injury and psychological abuse." (Reporting by David Schwartz in Phoenix, Arizona; Editing by Eric M. Johnson and Alan Raybould)