COLUMBIA — Two people went to the hospital and two homes were destroyed when an underground natural-gas pipeline in Adair County exploded early Thursday.
The blast badly damaged a third home, damaged several vehicles and spewed flames visible for miles, authorities said.
The two people who went to the hospital were not seriously injured. They were released after treatment, said Gale Cowan, deputy director of emergency management for the county.
The powerful blast happened about 2 a.m. on a hill in the Knifley community, in the northern part of the county, about 100 feet away from KY 76, the main road through the area.
The explosion opened a crater 40 to 60 feet wide, tossed a piece of the pipeline across the road and covered it with debris.
"It looked like a gravel field," Cowan said of the road. The road was closed most of the day, but officials hoped to reopen it Thursday evening.
Emergency responders evacuated about 20 homes in the area as a precaution, Cowan said.
The 30-inch line that exploded was about 20 feet underground. It is owned by Columbia Gulf Transmission.
Monitors on the line detected a drop in pressure caused by the explosion at 2:05 a.m.
The company used valves to isolate the damaged section of line, said spokesman Shawn Tolle.
The fire eventually burned out.
The cause of the blast was not known Thursday The company will work with federal investigators to figure out what caused the pipeline failure, Tolle said.
The explosion brought fresh fears to some residents who oppose a pipeline project that is securing land in several north-central Kentucky counties.
The Bluegrass Pipeline project would stretch about 180 miles through the state and carry flammable natural gas liquids to a connector that leads to the Gulf of Mexico.
"I think this is just a wake-up call for Kentucky that our legislators need to do something about this," said Cindy Foster, who lives near the pipeline's projected path in northern Scott County.
Opponents have asked the Kentucky General Assembly to clarify eminent domain laws so the pipeline developers cannot condemn land without consent from landowners.
Several bills addressing the issue have not moved out of House and Senate committees.
Officials at Williams Co., one of the companies behind the Bluegrass Pipeline, have said that their pipeline would be safe for nearby residents.
The line that blew up in Adair County is known as Line 200. A different section that passes through Estill County ruptured in January 2012.
No one was hurt, but officials evacuated 30 families.
Columbia Gulf Transmission is part of the Houston-based Columbia Pipeline Group, which has about 1,400 miles of pipelines in Kentucky.
A company spokeswoman said having two fires along the same pipeline system "does not mean that the pipeline facilities or circumstances are comparable."
Kentucky has been called "pipeline alley" because it lies between major refining operations on the Gulf Coast and customers in the Northeast.
There are about 7,500 miles of pipeline under the state, most of them natural-gas pipelines, according to the state Public Service Commission.
There have been a number of pipeline explosions in the state.
In the worst in the last three decades, five people were killed and four injured in April 1985 when a large pipeline exploded in Metcalfe County.
The next year, six people were hurt and two homes were destroyed in a pipeline explosion in Garrard County.
In March 2002, 30 families had to leave their homes when a pipeline blew up in Montgomery County.
Herald-Leader reporter Bill Estep and the Associated Press contributed to this article.