NEW ORLEANS -- Neighbors reported hearing a loud boom just after 11 a.m. Wednesday in Holly Grove after a breaker on a power-generating turbine at the Sewerage & Water Board's power plant blew and caught fire.

The plant, in part, powers the city's drainage pumps, drinking water and sewage systems.

A New Orleans Fire Department rescue truck and a full engine company raced to the plant as thick, black smoke billowed from the upper windows of a building at the S&WB's South Claiborne Avenue plant that houses the five turbines.

"It smelled like a wire or something was burning," said Johnny Wilson, who was sitting on his porch across the street from the plant when he says he heard the boom.

Paul Rainwater, one of the members of an interim management team running the agency, said no one was seriously hurt in the fire, but someone who tripped and fell refused treatment from New Orleans EMS for a strained ankle.

Turbine 4, one of the five large machines that is supposed to generate power for the S&WB, was taken out of service in 2012 after Hurricane Katrina damaged it.

After five years of repairs, cost increases and delays, turbine 4 was being re-installed at the power plant at a diminished capacity. City leaders said last week contractors were still waiting for parts needed to get it back to 100 percent.

"S&WB's goal is to stabilize the system as quickly as possible. According to consultants at CH2M, turbine 4 could be safely put back in service," said Erin Burns, Press Secretary for Mayor Mitch Landrieu.

But that didn't happen Wednesday.

"In the process of testing T4, just before 11:00 we had a spike in voltage which caused equipment failure and fire on electrical equipment related to a circuit breaker," Rainwater said.

Of the five turbines at the S&WB plant, only two were operational Wednesday.

Turbine 1 is a smaller power generator, pushing out 6 megawatts of old-fashioned 25-cycle power many of the S&WB's pumps rely on to run. Once fixed, Turbine 4 would provide a much needed boost to the system. It's designed capacity is 20 megawatts of 25-cycle power.

The only other turbine working Wednesday was Turbine 6, which generates more modern, 60-cycle power. It was build by the U.S. Army Corps of Engineers following Hurricane Katrina.

An August email from outgoing Superintendent Joe Becker, obtained through public records requests by WWL-TV and partner newspaper The New Orleans Advocate, estimated the cost of repairs to turbine 4 had climbed to $24 million.

Rainwater indicated Wednesday the fire did not directly affect the turbine.

"Turbine 4 itself was not damaged, but the circuit breakers related to that high voltage is what was damaged," he said.

While the state of operations in the drainage, sewer and drinking water systems will not be affected, the weakened state of the power plant continues to pose a hazard if severe weather strikes.

The installation of massive generators was expected to begin Wednesday, but didn't begin because of the fire.

The city and S&WB purchased the generators after rain water inundated the city on Aug. 5 and for the first time exposed vulnerabilities created by the S&WB's ability to generate power and run its drainage pumps.