A 19-year-old volunteer firefighter described by one Ocean County law enforcement official as a "serial arsonist" was sentenced Thursday to 11 years in prison.

Ryan Dellane of Manahawkin, who was in training with the Stafford Township Volunteer Fire Department when he was arrested, pleaded guilty earlier this year to setting nine fires. One of them, in March 2010, spread across more than 500 acres in the Pine Barrens and caused the evacuation of two towns.

In his confession to investigators, Dellane admitted that he began setting fires only two months after joining the department in 2008. He went on to ignite 25 fires, said Michel Paulhus, Ocean County executive assistant prosecutor.

The courtroom in Toms River was packed with firefighters and Dellane's friends and family, who offered conflicting testimony of a young man who would spend his spare time volunteering with local charities but who also would sneak into the woods to light fires that he later would help put out.

Clarence Mathis, a firefighter with the New Jersey Forest Fire Service, recalled Dellane working on a water truck during one of the fires.

"He was smiling and seemed to be enjoying himself," he testified.

The son of a veteran Stafford Township police officer, Dellane read a statement in which he apologized to his family and the assembled firefighters.

"I was stupid and immature when I set those fires," he said. "I have given the fire service a black eye."

Dellane's attorney argued that his client had been suffering from psychological problems and had since undergone therapy.

"He's still a kid," attorney Guy Ryan said. "Many of these offenses were committed while he was still in high school."

But the prosecutor painted a far different portrait of Dellane, whom he described as an "adrenaline junkie" who lit fires for thrills.

"This behavior is addictive," Paulhus said. "It makes him much more susceptible to reoffending."

Paulhus had argued that Dellane deserved a sentence 20 years.

Superior Court Judge Wendel Daniels ordered Dellane to serve his sentence in a youth correctional facility, which accepts inmates up to age 26. Dellane has agreed to pay restitution to the state and insurance companies for the damage caused by the fires, which Paulhus said would amount to "several hundred thousand dollars."

The Dellane family has a long history in law enforcement and the fire service, Stafford Police Lt. Thomas Dellane said. He asked the judge for leniency, describing his son as "hardworking but immature at times."

After the sentence was read, Dellane was handcuffed and allowed to hug his parents goodbye. He walked tearfully out of the courtroom, turning to a television cameraman and saying, "get that camera out of my face."

For the firefighters, the case will linger for a long time, said Donald Knauer, New Jersey Forest Fire Service section warden.

During the hearing, Knauer testified how firefighters under his command were almost killed fighting one of the fires Dellane set. One of the officers, who testified in court, suffered a second-degree burn on his back.

"Knowing the fire he lit injured a firefighter, Ryan still lit the next fire," Knauer testified. "It was heartbreaking. Ryan was never a firefighter, nor will he ever be. He is a serial arsonist."

Contact staff writer James Osborne at 856-779-3876 or jaosborne@phillynews.com.