A hearing over increasing safety at construction sites quickly boiled over into a tense scene between union and non-union workers in the chamber of the City Council. Our Courtney Gross was there today and filed this report.

The war between union and non-union labor spilled onto Broadway, and into the City Council chamber.

One developer and the head of the city's Building and Construction Trades Council mixed it up in one contentious moment.

At issue was safety at construction sites and how much workers are trained to deal with the risks of the job.

"We want to make sure that all construction workers at the end of the day go home to their families," said Gary LaBarbera, with the union.

The unions are pushing legislation to require construction workers go through an apprenticeship program or receive similar training to work on at a large construction job in the five boroughs.

Unions run these types of programs.

"I currently have in my possession 22 licenses and certifications, from OSHA, from the fire department, from my union and other entities," said one union worker.

Nonunion workers at the council's hearing did not have the same qualifications.

"L+M does require everyone to have a thirty hour OSHA card," said a nonunion worker. "So better training and safety is important."

The unions allege lives are at risk. Union workers rallying on Broadway say 30 people died in construction accidents over the last two years — 90 percent at nonunion sites.

Now some of the city's major real estate associations oppose the measure. People say it's too expensive and it wouldn't target the safety training these workers need."

The de Blasio administration also came out against the measure, arguing training required by its federal oversight agency would suffice.

"Safety is not a union matter," said Mayor Bill de Blasio. "It's a safe site or an unsafe site. We are not going down the road of requiring people to have apprenticeships."

Officials are targeting some reform, this is just one of 20 proposals the Council is currently considering.