(CNN) -- Two workers were rescued Thursday after at least 50 feet of earth collapsed into a sinkhole that appeared nearly two weeks ago in Assumption Parish, Louisiana, officials said.
The workers were on a boat that was tied to a tree when the land gave way, trapping them on the vessel, police spokeswoman Kim Torres told CNN in a telephone interview An airboat rescued them soon after; neither worker was hurt, she said.
In a statement, the company doing work on the site said the workers escaped from the sinkhole, which widened 50 more feet Thursday and is as big as a football field.
But the Houston-based Texas Brine Company, which owns the property, about an hour's drive west of New Orleans, said the workers sailed on the airboat away from the affected area before the collapse.
The situation is all the more worrisome because the hole is believed to be close to a well containing 1.5 million barrels of butane, a volatile liquid that turns into a flammable vapor upon release.
About 150 households have been evacuated, a state official said.
The widening of the sinkhole was no surprise. It "has been predicted by experts and has been gradually occurring since it first formed," said Texas Brine in a statement.
Torres said the two workers are employed by Clean Harbors, which describes itself as "the leading provider of environmental, energy and industrial services and the largest hazardous waste disposal company in North America."
Texas Brine Spokesman Sonny Cranch said the workers were removing debris floating in the sinkhole when at least one person aboard a rescue boat saw the land fall in and "immediately moved to a safer area, which happened to be a nearby airboat."
Authorities were investigating the cause of the hole, which has swallowed cypress trees up to 100-feet tall. The company has said that a nearby salt cavern could be to blame.
The cleanup operations that the rescued workers were involved in have been suspended as a precaution. Cranch said, "We don't want anyone in harm's way."