(CNN) -- Record floodwaters inundated parts of southern Louisiana early Tuesday after intense rains caused flash flooding and prompted hundreds of rescues.
Estimates by the National Weather Service put total rainfall at 12 to 18 inches across the region, with possible amounts of 20 or more inches in some areas. A flood warning has been issued until late Tuesday.
Floodwaters were cresting overnight for Bayou Vermilion at Carencro at 5.5 feet over flood stage and 12 inches above the record set in May 2004.
"We're still conducting rescues," Lafayette Parish Sheriff's Office spokesman Kip Judice said Monday evening. "We've done over 150 rescues throughout the day today."
One of those involved 16 middle school students whose bus became stuck after more than 4 feet of water covered the road.
"It was really scary because we couldn't get out of the bus ... the water was closing it in," said student Cory McCall. "It was thundering and lightning."
Boats and dump trucks were used to reach the children and bring them to safety, Judice said.
The town of Carencro was among the hardest hit communities in Lafayette Parish, according to Capt. Craig Stansbury, who is also from the Parish Sheriff's Office. He noted there were reports of water as high as 8 feet on some roadways.
Stansbury said fire department vehicles, tractors and conventional boats and airboats were being used to reach those stranded in homes and cars.
"A lot of things that we have at our disposal, we're just going to go ahead and utilize," he said. "Whatever it takes to get to the people."
The parish declared a state of emergency in the midst of the high water.
"We are working with local officials to ensure they get the resources and support they need to respond to the flooding," said Kevin Davis, director of the Governor's Office of Homeland Security and Emergency Preparedness. "We urge residents to be mindful ... and to take precautionary measures."
A state of emergency was also declared in St. Landry Parish, where Government Administrative Director Jessie Bellard estimated that some 2,000 people had been affected.
People were driving dump trucks to rescue residents who have flooding in their homes and can't get out. Bellard said several minor and major roads, including part of U.S. Highway 190, have experienced significant flooding.
"It's just a terrible situation," Bellard said.
Maj. Ginny Higgins of the St. Martin Parish Sheriff's Office said flooding affected at least 15 to 20 roads Monday in that parish. 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.
Stansbury, from Lafayette Parish, said residents knew Monday would be wet but didn't foresee the volume or intensity.
"There was a forecast of some heavy rains, but I don't think anybody could have predicted that amount of rain," he said.
And while the worst precipitation is over, the headaches are not.
Intermittent rain continued to fall.
Judice, from Lafayette Parish, said water levels were continuing to rise in his area.
"It's still a very crazy situation," he said.
CNN's Joe Sutton and Barbara Hall contributed to this report.