PHILADELPHIA — The Philadelphia Inquirer experienced the most significant disruption to its operations in 27 years due to what the newspaper calls a cyberattack.

The company was working to restore printing operations after a cyber breach prevented the printing of the newspaper’s Sunday print edition. reported the Inquirer on its website.

The news operation’s website was still operational on Sunday, though updates were slower than normal, the Inquirer reported.

Inquirer editor Lisa Hughes said Sunday that «we are currently unable to provide an exact timeline» for a full restoration of the newspaper’s systems.

«We appreciate everyone’s patience and understanding as we work to fully restore systems and complete this investigation as soon as possible,» Hughes said in an email responding to questions from the newspaper’s newsroom.

The attack was first detected when employees discovered Saturday morning that the newspaper’s content management system was down.

The Inquirer «discovered anomalous activity on selected computer systems and immediately took those systems offline,» Hughes said.

The cyberattack has caused the biggest disruption to the publication of Pennsylvania’s largest news organization since a massive snowstorm in January 1996, the Inquirer reported.

The cyber attack precedes a mayoral primary election scheduled for Tuesday. Hughes said the operational disruption would not affect news coverage of the election, although reporters would not be able to use the newsroom on election night.

Hughes said that other Inquirer employees will not be allowed to use the offices until at least Tuesday, and that the company was seeking coworking arrangements by Tuesday, the Inquirer reported.

An investigation was underway into the scope and specific targets of the attack, and the company contacted the FBI, Hughes said.

The FBI in Philadelphia declined to comment in response to questions from Inquirer reporters, the newspaper reported.