Frustration is mounting in the evacuated town of High River as some residents ask to return to their homes.

About 13,000 residents have been under a mandatory evacuation order since Thursday when a state of emergency was declared as rising floodwaters from the nearby Highwood River burst over the banks.

On Monday, local politicians urged patience, saying that with no power or water and unsafe roads, residents can't enter.

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Houses and a golf course are surrounded by flood water in High River, south of Calgary on Sunday. High River was one of the hardest hit communities from the flood waters. (Andy Clark/Reuters)

"We need folks to stay away from the town of High River," said Mayor Emile Blokland on Monday. "It’s not a safe place to be. We are still without much of our critical infrastructure. We have nothing in the way of supplies for you once you get here. We need you to stay away."

A 24-year-old man armed with a knife tried to breach the security perimeter Sunday night, saying he wanted to check on his dog.

"We believe that it is just a sense of frustration on this person’s part. For the most part, people are being as patient as they can be. We recognize this is an ongoing and very tragic situation. We are asking for people's patience," said RCMP Cpl. Laurel Kading.

Pets are being rescued and sent to shelters, police said. A Facebook page has been created so owners can see pictures of the animals that have been recovered.

'This is crazy'

Courtney Charles can see her home, still dry, across the expanse of floodwater, but she can’t get in to obtain her son’s medication.

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Residents look across floodwaters at their homes in High River. (CBC)

"This is crazy. We just need to get in for certain stuff. Give us five minutes, man, escort us in," she said. "I have four kids. We're homeless. All of our food, all of our possessions [are in there]. We left with the clothes on our back."

Officials said it could be days, even a week, before people can return.

Police officers are going door-to-door searching for those who have insisted on staying behind. On Sunday, about 350 members of the Princess Patricia's Canadian Light Infantry from Edmonton were assisting local RCMP in reaching homes that had not yet been checked.