A 14-year-old boy has been arrested in the vicious attack on an elderly Queens man outside a public library, police said.

The teen, whose name was not released, is the third suspect to be busted for beating up 79-year-old Joseph Bonaventure outside the Cambria Heights branch of the Queens Public Library on Oct. 1.

18-year-old Nyziere Lodge and a 15-year-old boy were caught earlier this week. All three have been charged with gang assault. Lodge and the 14-year-old teen were also charged with disorderly conduct, police said.

Bonaventure told the Daily News he was trying to walk past the roughhousing boys when they turned on him.

One of them allegedly screamed, “Let’s get him!”. They chased the retiree a block and jumped him. The disturbing attack was caught on a cell phone video, which police released Tuesday.

Lodge was arraigned in Queens Criminal Court on Monday and ordered held on $20,000 bail.

Bonaventure was left with six broken ribs and a broken hip, and told The News he may have to stay in rehab for several months.

“I hope they (the teens) change their mind. I’m 79-years-old. I’m on my way out,” he said. “But this will be a blemish on their records for the rest of their life. I hope they change their ways.”