The Free Library of Philadelphia, Cecil B. Moore Branch, sits right next door to an abandoned building.
Officials say the thieves used an abandoned building next door to launch their attack, using heavy construction tools to break through a brick wall and another wall to get inside.
Patrons are furious.
"They can knock down walls, they can have jobs in construction, but they'd rather come in and steal!" Trelania Carter of North Philadelphia said.
The intruder stole computers that were absolutely free to use at the library.
There are now empty spaces where eight monitors, six towers, keyboards, and accessories used to be. Signs greeted dismayed patrons, alerting them to the thefts and diverting them to other branches.
"It makes me sick to my heart that people are so desperate they'd steal something from a free library," Marjorie Lazenby of North Philadelphia said.
To add insult to injury, there's no guarantee the computers will be replaced. With drastic budget cuts, the sign explains, funding is not available.
For these North Philadelphia patrons, the thief did more than steal; the culprit cut off the lifeline for so many people that are already in need.
"I get food stamps at the library. I apply for them here, I apply for unemployment here. A lot of people do. I can't afford a computer. Most people here can't afford a computer," said Lazenby.
Police say there is no surveillance footage to aid in this investigation, so investigators are asking anyone with information to give them a call.
