Five houses in a Prince George’s County neighborhood have been deemed unsafe and 23 others have had to be evacuated after a chunk of earth dislodged beneath the properties over the weekend and slid downward, triggering a water main break and destabilizing the road to the homes.

And for residents it is not clear when they’ll be able to return.

Prince George’s County government officials said the road collapse occurred on Piscataway Drive in Fort Washington. Geo-technical engineers called it a “slope failure,” a sort of lower-grade landslide.

The strip of land that is collapsing is about 1,500 feet long, said Darrell Mobley, director of the county’s Department of Public Works and Transportation. Trees up to 200 feet tall are falling, taking power lines with them.

Now officials are rushing to assess the situation and devise a plan for restoring the area’s structural integrity.

“It will take at least two weeks timeframe for them to determine an appropriate short term solution to the problem,” Mobley said. “It’s too early to determine” when residents can return.

The soil, which contains Marlboro clay, is known to become unstable when exposed to air and water, county officials said.

A dramatic crack has split the middle of a street in the neighborhood, made up of large, single-family, custom-made houses.

Officials said they saw Piscataway Drive, a dead-end street that cascades downhill to the Potomac River tributary Piscataway Creek, start to crack over the weekend. County and Washington Suburban Sanitary Commission workers went to the area three times to repair the break but eventually told residents Sunday the situation had deteriorated, said Aubrey Thagard, assistant deputy chief administrative officer for the county’s office of economic development and public infrastructure.

Prince George’s officials are hoping to have more information on Tuesday about the sloping, but they said they think the significant rainfall last week may have caused the soil to shift.

But some frustrated residents said the sloping land is not a new problem.

“We have had smaller mudslides for the last 10 years,” said homeowner Dawn Taylor. “The county has come and patched-job the cracks in our slopes but they have not fixed it.”

Resident Sue Howland arrived on the scene and burst into tears. Her husband is an amputee who can’t get around on his own, and she takes care of 20 cats.

“This is our dream house and I didn’t know if we’re facing never seeing it again,” said Howland, who, overcome with emotion, fell into a county employee’s arms.

Officials were working to help her husband out of the home and find shelter for the couple as well as their pets.

An information center has been set up at Harmony Hall Regional Center on Livingston Road. County officials will work with the American Red Cross to shelter displaced homeowners, though many said they would be staying with friends or family. Family services also will be providing meals at Harmony Hall to those forced to evacuate.

At least one resident didn’t understand why county officials were forcing people out.

“I don’t want to leave, the county is being unreasonable,” said John Schnizlein, waving his orange mandatory evacuation notice that had been taped onto his front door.

Schnizlein, a 19-year resident of the neighborhood, said the water main has broken several times before and he, along with several neighbors, is determined to stay.

“Our goal is to get you back as soon as we can, safely,” Gary Cunningham, of the county’s Department of Permitting, Inspections and Enforcement, told Schnizlein.

But Schnizlein was determined to stay. He said if he needed water for the bathroom he would get it from the nearby creek.