01:03 ‘Total Disbelief’: Families Isolated as Isaias Washes Away Only Road to Their Homes Heavy rain and rising waters washed away a private road in Huntingtown, Maryland, stranding 7 families on the wrong side of the break.

At a Glance Homes are flooding in Fort Smith, Arkansas.

Flooding threatens of communities in Arkansas, Oklahoma, Kansas and Missouri.

Tulsa's mayor warns that levees are under unprecedented pressure.

At least 11 people have died in the flooding and severe storms. Residents all along the Arkansas River on Monday were preparing for the worst flooding in recorded history as the river hit record-breaking levels and was still days away from cresting.

Near Fort Smith, Arkansas, the river topped its historic crest on Sunday and isn't expected to crest this week until late Tuesday or early Wednesday.

City spokeswoman Karen Santos told the Associated Press that one home was completely submerged and about 500 homes either have water very close or in them. Hundreds more homes and businesses could flood by the time the river crests.

Across the river in Oklahoma, the tiny town of Moffett was already submerged, Sequoyah County Emergency Management Director Steve Rutherford told the Times Record in Fort Smith.

In Tulsa, Oklahoma, authorities warned residents to consider leaving for higher ground as the levees there are being stressed like never before by the release of water from the Keystone Dam.

“They were built for a reason and they are there to protect people. And they are protecting people right now,” Tulsa Mayor G.T. Bynum said Saturday during a news conference. “But they are also over 70 years old, and they are earthen levees. And they have never been tested like they will be over the next four or five days.

“I’ll tell you something. We’re in a very precarious situation right now ," Tulsa County Commissioner Karen Keith told the Tulsa World. "The levees have never had this much water on them for so such a long period of time. We’re going to be very fortunate if it doesn’t turn into a serious situation.”

Braggs, Oklahoma, was completely cut off by flood waters and had no electricity, the Associated Press reported. Oklahoma Department of Emergency Management spokeswoman Keli Cain said about 260 residents live in Braggs and it is not clear how many people evacuated before the flooding began.

David Williams, chief of hydrology and hydraulic engineering for the U.S. Army Corps of Engineers Corps’ Tulsa District, told the Tulsa World, “We are experiencing a historic flood not only in Tulsa but in all of northeast Oklahoma. We have been experiencing a moderate flood along the Arkansas River in Tulsa. We are experiencing a catastrophic flood in Muskogee and points below that location. In fact, the flood in those locations may be the flood of record.”

In Tulsa, the levees were being stressed by increased water released from the Keystone Dam.

The Army Corps of Engineers was expected to increase the release rate from the dam to 275,000 cubic feet per second. That rate will continue until at least Wednesday — 12 times longer than the 12 hours the levees bore before the city's flood of record in 1986, according to the Tulsa World.

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Officials in Greenwood County, Kansas, called for the immediate evacuation of people living below the Fall River Dam, about 70 miles east of Wichita. Water is being released from the reservoir at record levels, and widespread flooding is expected. Another 45 miles to the southeast, residents in parts of Coffeyville, Kansas, were ordered to leave their homes because of the rising Verdigris River,

Residents of West Alton in eastern Missouri, where the Mississippi River is expected to crest two feet above major flood stage in the coming days, also have been asked to evacuate.

Meanwhile, severe weather and flooding has claimed the lives of 11 people over the past week, including two people killed in a tornado Saturday in El Reno, Oklahoma, and two people who went missing on May 15.

On Friday, the bodies of John Reinhardt, 20, and 19-year-old Caitlin Frangel, both of Hazelwood, Missouri, were found dead in a car submerged in flood waters near the Mississippi River about 40 miles north of St. Louis, the Associated Press reported.

Trooper Dallas Thompson of the Missouri State Highway Patrol said an autopsy determined that they drowned.

(MORE: Tornadoes Along Oklahoma-Texas Border Damage Homes, Force Residents to Seek Shelter)

Thompson said authorities believe the vehicle became trapped after driving into the flooded area in the dark and the couple was unable to escape, according to the AP report. He added that it's unclear when the vehicle drove onto the flooded roadway, but that area of St. Charles County has been flooded for several days.

The days-long run of severe storms, tornadoes, heavy rains and flooding had already claimed seven lives, including three who died in a tornado Wednesday in Golden City, Missouri.

Two children were injured when they were hit by a car while playing in flood waters near Wichita Friday evening. Both were taken to the hospital, one in critical condition, KAKE reported.