CNN  — 

Maryland Gov. Larry Hogan declared a state of emergency Sunday in Howard County as a massive storm drenched the Baltimore region, triggering flash floods in Ellicott City and leaving one person missing.

Thirty rescues were carried out into Monday morning, officials said.

Main Street, also known as Frederick Road, was transformed into a waterway over the weekend, as brown water sluiced through town, destroying shops and upending cars. In some areas, the water rose above the buildings’ first floors.

One person was missing following the Ellicott City flooding, Howard County Executive Allan Kittleman said Monday morning. The circumstances were not immediately known. No fatalities were reported.

The devastation was especially hard to comprehend coming barely two years after the last flood that ravaged the city, he said. The disaster left two dead and damaged dozens of buildings.

Kittleman said the flooding was worse than that endured in July 2016. Gas lines were shut down and a historic building fell, he told reporters.

The city rallied around the slogan “Elliott City Strong.” Many businesses had just finished rebuilding, Kittleman said.

When the rain came Sunday, many residents remained in the throes of recovery. The county was working on stormwater retention ponds and preparing to install additional piping. Money from a Federal Emergency Management Agency grant had just arrived and was slated for repairs and construction, Kittleman said.

Advisories in effect

Ellicott City is an unincorporated community about 12 miles west of Baltimore. Located in the valley of the Patapsco River, a major waterway flowing to Chesapeake Bay, Ellicott City is known for its flood-prone location as much as its historic downtown.

The river rose 17.8 feet in two hours Sunday – to 24.1 feet, a record from the previous high of 23.6 feet. The National Weather Service, which issued a flash flood warning, reported greater Baltimore got isolated rainfall of more than 9 inches. Three to 6 inches was common in the metro area.

The National Weather Service issued a flash flood warning for northeastern Anne Arundel County and southeastern Howard County through earl Monday.

Another inch could fall Monday, the NWS said, and though that doesn’t sound like much rain, it means trouble for the already saturated ground and burgeoning rivers. Aside from the Patapsco River, there are four other smaller waterways running through and around Ellicott City.

Gov. Larry Hogan toured the area Sunday with Kittleman. He lamented the destruction, noting that two weeks earlier, he visited the historic downtown and spoken with business owners about rebuilding.

Close to 8 p.m., a Howard County Sheriff’s deputy moved a CNN crew and others in the area due to a suspected gas leak.

Multiple rescues are under way. Howard County Fire and EMS urged residents to evacuate downtown or move to higher ground while rescue teams swarmed the area.

The Roger Carter Community Center is open for those who need a place to shelter.

Hogan toured the area Sunday with Kittleman. He lamented the destruction, noting that just two weeks earlier, he had visited the historic downtown and spoken with business owners about rebuilding efforts.

“The place looked terrific,” he said. “It’s just devastating because people have their lives tied up in this and went through a heck of a lot and came back and now they’re starting all over again.”

Kittleman said state and county resources would be made available to those who want to rebuild again.

He declined to answer a reporter’s question about what could have been done differently to minimize the damage. The focus is on rescue and recovery, he said.

“Right now we’re focusing on people’s lives.”

CNN’s Amanda Jackson, Lindy Royce, Suzanne Malveaux, Liz Turrell and Gene Norman contributed to this report.