DES MOINES, Iowa — A levee ruptured here early today, allowing the Des Moines River to pour into an area near downtown. A mandatory evacuation was ordered for 270 homes, authorities said.

Crews from the city and National Guard used dump trucks and front-end loaders to build a temporary berm of dirt and sandbags in a bid to stop the water before it flowed out of the largely business area and into more populated neighborhoods.

The river punched a 100-foot-wide gap through the levee at about 3:45 a.m. in the city's Birdland Park area, and within a few hours water was up to 4 feet deep in places. Water also had surrounded much of North High School.

"We have a pretty strong gush of water coming through that area," said police Sgt. Vince Valdez.

Many residents of the area already had left after a voluntary evacuation request was issued Friday, but Neil Schultz of the Polk County sheriff's office said officers were going door to door today to ensure that everyone had left.

The breach came only hours after the river had crested at Des Moines and started to recede, but officials said the levees remained at risk.