At least 27 people are dead, including nine children, after heavy rain caused catastrophic flooding in Texas.

Officials are still searching for 24 girls missing from Camp Mystic, an all girls camp along the Guadalupe River, Dalton Rice, manager of the city of Kerrville, Texas, said at a press conference Saturday.

While search and rescue operations remain ongoing, officials said they do not have an accurate count of how many people are missing and said they would not provide an estimate.

Rice said rescues are occurring from camps that were isolated because of road damage.

A flash flood emergency has been issued by the National Weather Service for northwestern Travis County and far eastern Burnet County around Lake Travis in south-central Texas until 5 a.m. CT.

Between 3 inches and 7 inches of rain have fallen in the area north of Lake Travis, the service said. Some spots measured over 10 inches of rain over the past few hours, with peak rainfall rates reaching 6 inches per hour.

Rainfall of up to 5 inches was still expected in some areas. The service described the local weather as a "particularly dangerous situation," a high-level warning that carries urgency.

"Seek higher ground now!" forecasters said.

-ABC News' Kyle Reiman

President Donald Trump described the flooding in Texas and subsequent deaths as "terrible," adding that he's working with Texas Gov. Greg Abbott to coordinate possible federal aid and to mitigate the damage.

"They don't know the answer yet as to how many people, but it looks like some young people have died," Trump said Friday on Air Force One, referring to the deaths as "shocking."

Asked if the federal government will send federal aid, the president replied, "Oh yeah, we'll take care of it. We're working with the governor."

-ABC News' Emily Chang

A Texas official said the forecast provided by the National Weather Service underestimated the amount of rain that lashed central Texas before devastating flooding.

Nim Kidd, the chief of the Texas Division of Emergency Management, said the original forecast received on Wednesday from the weather service predicted 3 to 6 inches of rain in the Concho Valley and 4 to 8 inches of rain in the Hill Country.

The state emergency operations center began daily briefings Thursday on the potential for flooding.

"But listen, everybody got the forecast from the National Weather Service, right?" Kidd said during a news conference Friday, adding, "It did not predict the amount of rain that we saw."