A Midwood-based construction company knew that its Brighton Fifth Street building was unstable, but rushed to complete it anyway, federal officials said Tuesday as they slapped the contractor with $77,880 in fines for causing a collapse that killed one worker and injured four others.

The Occupational Safety and Health Administration hit SP&K construction with 11 violations on Tuesday, claiming that the company was aware that its steel building was unstable.

“Had proper procedures and safeguards been followed, [the collapse] could have been prevented,” said Kay Gee, the Occupational Safety and Health Administration’s Brooklyn director.

Investigators said employees were told to begin pouring concrete on the top three floors of the five-story building near Oceanview Avenue on November 8 — before the concrete on the lower floors had hardened.

The structure buckled under its own weight, burying seven workers in debris.

Two workers were able to make it out of the rubble on their own. Firefighters found the rest after a short search, but one of the men suffered a heart attack and died after being rushed to Coney Island Hospital.

Federal officials say SP&K Construction has two weeks to either pay the fines or file an appeal.

Brighton Beach residents feel the company should pay up.

“They wanted to get the job done as quickly as possible,” said Brighton Beach resident Judd Fischler. “There was no supervision.”

SP&K Construction did not return calls for comment.

Reach reporter Daniel Bush at dbush@cnglocal.com or by calling (718) 260-8310. Follow him at twitter.com/dan_bush.