An off-duty NYPD officer is recovering from a fractured skull following an attack Tuesday morning in the Bronx.

Police say the 48-year-old off-duty officer was jogging on Olmstead Avenue when he was approached by three people who began hitting the officer on the head repeatedly before taking off with his cellphone, car keys and wallet.

The officer was taken to a hospital, where he's being treated for a brain bleed. The name of the officer has not been released. He is in critical but stable condition, according to police.

The police commissioner confirmed that the off-duty officer is one of the victims attacked in what police are now calling a citywide robbery pattern.

The Police Benevolent Association released a statement, saying in part, "Police officers across this city are searching for the cowards who did this to him. Make no mistake: we will find them. But we will need the rest of the justice system to step up and do its job, too."

The suspects are wanted in at least 18 other attacks and usually include four people. Police say what happens in most of these attacks is three people approach the victim while a fourth person waits in a car. In some of the hits, the thieves even have a gun on them, and the getaway car has frequently been a black Honda sedan.

Eighteen of the 19 incidents were in the Bronx, with the other in Queens. All took place since the start of August.