A house sits isolated by floodwaters from the Red River on Sunday south of Fargo, N.D.

Fargo, N.D. ? Weary residents of this sandbagged city came together in churches Sunday, counting their blessings that the Red River finally stopped rising and praying the levees would hold back its wrath. A brief levee break that swamped a school warned them of the threat they face in days ahead.

Church services that are a staple of life on Sunday mornings in Fargo took on greater significance after a week of round-the-clock sandbagging. Worshippers sang hymns and held hands, asking together for divine help in avoiding disaster.

“At a time like this, we need to call on God’s providential assistance,” said the Rev. Bob Ona, pastor of Fargo’s First Assembly of God church. “All of you have been heroic in your efforts. All of you have been pushed past the wall of weariness, exhaustion and numerous frustrations in order to do the right thing: Help people in the name of the Lord.”

The Red River continued its slow retreat Sunday after cresting a day earlier, dropping from its record level to 39.71 feet. City officials have said they would breathe easier when the river falls to 37 feet or lower, expected by this Saturday, meaning a lengthy test for sandbag levees that residents hastily constructed last week.

Fargo faced another test this week as a storm approached with up to a half-foot of snow and powerful wind gusts that could send ferocious waves crashing into and over the already-stressed levees.

The sandbag effort resumed Sunday as helicopters began dropping 11 one-ton sandbags into the river to deflect its violent current and keep it from eroding vulnerable areas of the dike system. A helicopter also was used to lower a 3,000-pound concrete weight onto an ice jam that was causing river levels to rise at Oslo, Minn., about 25 miles north of Grand Forks.

“They tried it, but there wasn’t much success to it,” Oslo city council member Scott Kosmatka said.

The aerial effort also included an unmanned Predator drone used to watch flood patterns and ice floes and provide high-definition information to teams on the ground. North Dakota has more than 2,400 National Guard troops engaged in the flood fight across the state.

The helicopter sandbag effort was focused on an area of the river where waters burst past a levee early Sunday and submerged a Lutheran school campus.

Oak Grove Lutheran Principal Morgan Forness said city officials, the Army Corps of Engineers, and the National Guard unsuccessfully tried to contain the gushing water after a floodwall buckled around 1:30 a.m. The water kept spreading and “we couldn’t contain it. … it’s inundating all of the buildings,” Forness said.

“The campus is basically devastated. They fought the good fight. They lost, and there’s nothing wrong with that,” Mayor Dennis Walaker said. “Those things will continue to happen. I guarantee it.”

Crews largely contained the flooding to the campus, preventing more widespread damage in nearby areas. School officials also frantically raced to rescue a cockatiel, parakeet and tortoises, birds, iguanas and snakes kept at the school as part of its science program, while pumping out most of the water in the buildings within 12 hours.

The flooding at the campus — heavily damaged in the region’s 1997 flood — represented the type of disaster that could crop up in Fargo throughout the week, with Walaker calling it a “wake-up call” for the city.