A woman who set her boyfriend's duplex apartment on fire – causing the injury of two brothers living in the other unit – has been sentenced to six years in prison.

Deanna Lee Thielbar, 47, pleaded guilty last month to first-degree arson and was hit with a stiffer than usual sentence for the crime by Ramsey County District Judge Leonardo Castro Tuesday, the Pioneer Press reports.

Thielbar started a fire in the lower apartment unit of her boyfriend Dennis Johnson's home in St. Paul's West End in July, which prompted the rescue of brothers Richard and Louis Stauch, then aged 67 and 65 respectively, from their second-floor apartment.

The Ramsey County Attorney told BringMeTheNews that there were aggravating factors that increased Thielbar's sentence, namely that the victims were vulnerable, she failed to call emergency services, and she endangered multiple people.

"Arson is is a very serious crime, thus we feel this sentence sends a strong message to those who would recklessly put lives in danger," Ramsey County Attorney John Choi said. "I am relieved that we gained some measure of justice for the victims in this case."

The Pioneer Press says neighbors heard Thielbar arguing with her boyfriend in the lead-up to the blaze, before reporting two loud explosions coming from the back of the house. The fire consumed the garage and rear of the house at 422-424 Goodrich Ave.

Richard Stauch was rescued by teenagers Luis Ramirez and Ricardo Martinez, who used a ladder to climb into the apartment and pull him to safety, before his brother Louis Stauch was rescued by firefighters. They both suffered burns and smoke inhalation injuries.