“The drive to Bellevue Hospital, the chaos, and the sea of uniforms in and out,” Officer Laurie’s wife, Adelaide Laurie, recalled.

Image Officer Laurie

“Please don’t let it be that we are retrogressing to that horrible time in the ’70s,” Ms. Laurie said in an interview on Sunday. She added: “It’s the same idea. No one trusted the police; they were called pigs. I’m just kind of reliving that tragedy all over again.”

For many police officers who grew up in the aftermath of these killings — or had relatives who were on the police force at the time — the link to that harrowing past is both sentimental and real. Officer Ramos, killed on Saturday, once served as a school safety agent at Rocco Laurie School on Staten Island.

The Black Liberation Army also took responsibility for the fatal shooting of Officers Joseph A. Piagentini and Waverly M. Jones by two assailants outside the Colonial Park Houses in Harlem in 1971. In 1975, three members of the Black Liberation Army were convicted of murder in the case.

Police Commissioner William J. Bratton, speaking on the NBC “Today” show on Monday, said the killing of the two officers on Saturday reminded him of the department’s unease in the 1970s.

“My first 10 years were around this type of tension,” Mr. Bratton said. “Who would’ve ever thought, déjà vu all over again, that we’d be back where we were 40 some-odd years ago?”