A burst of intense rain caused perilous flash flooding Monday in parts of Louisiana, spurring the evacuations of hundreds of people and cutting off many more residents after high waters covered roads.

(CNN) -- A burst of intense rain caused perilous flash flooding Monday in parts of Louisiana, spurring the evacuations of hundreds of people and cutting off many more residents after high waters covered roads.

According to the National Weather Service, southern Louisiana was pelted with an estimated 15 inches of rain in six hours, with on-and-off rain continuing for hours after that.

"People that have lived here many years ... said they hadn't seen flooding like this," said Capt. Craig Stansbury of the Lafayette Parish Sheriff's Office. "There was a forecast of some heavy rains, but I don't think anybody could have predicted that amount of rain."

One of the worst hit areas was St. Landry Parish, where Government Administrative Director Jessie Bellard estimated 2,000 people had been affected thus far. A state of emergency has been declared for the parish, though there are no known injuries or fatalities there or elsewhere related to the flooding.

People were driving dump trucks to rescue residents who have flooding inside their homes and can't get out. He said several minor and major roads, including part of U.S. Highway 190, have experienced significant flooding.

"It's just a terrible situation," said Bellard.

The town of Carencro was the hardest hit community in Lafayette Parish, according to Stansbury, noting reports of water as high as 6 to 8 feet on some roadways.

Stansbury said fire department vehicles, tractors, dump trucks and conventional boats and air boats were being used to reach those stranded inside homes and in cars.

"A lot of things that we have at our disposal, we're just going to go ahead and utilize," Stansbury said, estimating at least 80 people needed to be rescued. "Whatever it takes to get to the people."

Maj. Ginny Higgins of the St. Martin Parish Sheriff's Office said at least 15 to 20 roads were affected by flooding Monday. Several people were safely rescued after being trapped in their vehicles, she said.

A state of emergency has been declared for that parish, Higgins said.

While not falling with the same intensity as it did earlier, rain was forecast to continue to be a problem all Monday night.

A National Weather Service-issued flash flood warning was in effect for all or parts of the parishes of Central Allen, Evangeline, Acadia, Lafayette, St. Martin and St. Landry through 11:30 p.m.

"This continues to remain a dangerous situation, with numerous roads and homes flooded," the service said in the warning.

CNN's Joe Sutton and Barbara Hall contributed to this report.