A fire that broke out at a natural gas plant in Westbrook on Monday afternoon was brought under control about three hours later.

Westbrook Fire Chief Stephen Sloan said several fire departments responded to the fire around 2:15 p.m. at the Westbrook Energy Center, 60 Eisenhower Drive. The plant, which is operated by Calpine Corp., burns natural gas to produce electricity, Sloan said.

Sloan said the fire broke out on the upper floors of the eight-story power plant and spread to the roof. No injuries were reported and the fire does not appear to be suspicious, though the cause remains under investigation.

The extent of damage to the plant was not clear Monday night.

The Westbrook Energy Center produces enough electric power to meet the needs of more than 500,000 homes throughout New England, according to the company’s website. The energy center was among the first of a new generation of power plants built to sell competitively priced wholesale electricity into the region’s electric power grid.

Calpine Corp., which owns and operates the plant, said the Westbrook Energy Center is the city’s largest taxpayer.

Calpine Corp. bills itself as America’s largest generator of electricity from natural gas and geothermal resources. The power company was founded in 1984.