LITTLE ROCK — Work continued Monday to clean up a crude oil spill that threatened Lake Conway in Faulkner County, Gov. Mike Beebe said.

Cleanup crews have deployed 3,600 feet of boom near the lake as a precaution, but no oil has reached the lake, the Mayflower police said in a news release.

The governor said about 12,000 barrels of oil and water had been recovered.

"They’ve got a lot of people on site and it is a top priority to get it fixed," Beebe said after attending a news conference at the old State House to celebrate the 100th anniversary of the Arkansas Department of Health.

"They’re trying to determine what caused it," he said about the crude oil pipeline break first reported Friday. Twenty-two homes on Starlite Road and Shady Tree Lane in the Northwood neighborhood in Mayflower were evacuated after the oil spilled into a creek and flowed down a street and into yards.

ExxonMobil, which owns the pipeline, had about 120 workers at the scene, along with federal, state and local officials working to contain the spill. Fifteen vacuum trucks and 33 storage tanks were also deployed to the site to clean up and temporarily store the oil.

The Environmental Protection Agency has categorized the incident as a "major spill," the Mayflower police department news release said, because it was greater than 250 gallons.

The cause of the leak was unknown Monday morning.

"As I understand it, it’s a pretty old pipeline," Beebe said. "I don’t know what sort of evidence they’ve got maintenance issues may have caused it, or it’s just a function of age, but you know it sends a signal that while we have to have pipelines, and certainly that’s an effective way of moving crude, and while we’ve all got to have oil for our vehicles, there has to be a concomitant interest and effort in safety."