Fort Lauderdale declared a state of emergency on Thursday after a deluge of rain flooded a number of roads and shut down a major airport.

“Flooding conditions remain impactful in the southern areas of the City this morning. An active emergency declaration is in effect,” said the City of Fort Lauderdale on its website. “Emergency Management crews worked continuously through the night to attend rescue calls.”

It did not say when the state of emergency would end.

In a 10:30 a.m. update, the city said that “many roads across the City are still impassable due to flooding” and urged people to “avoid driving” when possible. “Crews are out in neighborhoods clearing storm drains to aid water receding from neighborhoods. Vacuum trucks are being deployed strategically throughout the City. However, because of the extreme amount of water, most areas will need to drain naturally,” the update said.

The U.S. National Weather Services said that upwards of 26 inches of rain fell in Fort Lauderdale on Wednesday, with most falling in the span of only a few hours. Shawn Bhatti, a meteorologist with the National Weather Service in Miami, told the Florida Sun-Sentinel that the rainfall total is “an unprecedented event.”

Broward County schools canceled classes Thursday, including after-school and extracurricular activities, after water flooded hallways and classrooms at some schools. Service was restored on South Florida’s high-speed commuter rail, Brightline, after it briefly shut down Wednesday evening.

Fort Lauderdale Hollywood International Airport, which closed Wednesday evening, said it would not reopen until 5 a.m. Friday because of debris and massive flooding.

More showers, thunderstorms and local flooding were in the forecast from the National Weather Service on Thursday. An additional 2 to 4 inches of rain was possible.

A severe thunderstorm watch is in effect for much of northeastern Florida as of Wednesday afternoon, according to the Weather Service.

Shawn Bhatti, a meteorologist with the National Weather Service in Miami, said the region received “an unprecedented amount” of rain. The weather service was still confirming totals, he added.

“For context, within a six hour period the amount that fell is about a 1 in 1,000 chance of happening within a given year,” Bhatti said. “So it’s a very historical type of event.”

Fort Lauderdale City Hall remained closed Thursday with ground-floor flooding and no power. A tunnel housing U.S. Route 1 under a river and a major street in downtown Fort Lauderdale was also closed, along with some ramps to Interstate 95.

At a news conference on Thursday, Fort Lauderdale Mayor Dean Trantalis told reporters that city residents should “be patient as some say this was a one thousand year storm that resulted in the weather service issuing a very rare flash flood alert.” The city, he said, is contacting federal and state officials for assistance.

“If someone is in a really bad emergency, they should call 911,” he said. “For non-emergencies, call 954-828-8000.”

Meanwhile, the National Weather Service confirmed there were two EF-0 tornadoes near Dania Beach on Wednesday amid the heavy rainfall.

The Associated Press contributed to this report.