They were all heroes on that day.  And it seemed for days like we were all connected.

Police Officer Robert Oswain, a Bronx cop who served in recovery efforts at Ground Zero, died of cancer late Saturday. He was 42.

Police Commissioner Raymond Kelly commended Oswain, who had recently married, for his “valiant struggle” against the disease. He expressed condolences to Oswain’s family.

“He served the public as a police officer assigned to the 47th Precinct in the Bronx, and he served his fellow officers, and the nation at large, in the recovery efforts in the aftermath of the terrorist attack that destroyed the World Trade Center on 9/11,” Kelly said in a statement.

Oswain’s family and NYPD brothers believe Ground Zero’s toxic dust caused the cancer that claimed his life.

Patrolmen’s Benevolent Association President Patrick Lynch called Oswain “one of the forgotten heroes of 9/11” – and warned that the true cost in lives from the attacks won’t be known for decades.

“More must be done on a federal level for the thousands who answered the call without question and were stricken from toxic exposure,” Lynch said.

Oswain’s father, Robert Oswain Sr., said the family did not wish to speak publicly about his passing yesterday. But he wanted to thank the officers of the 47th Precinct for their support.

“Nothing but the best,” Oswain said. “It’s remarkable how they take care of their own.”