"It was one person and they knocked at five or six houses. Whether it was malicious or just a brain fade, it's not helpful to those people in that area. Put yourself in their shoes and think how you would feel.
"We know most of the residents in that area by name and some of them are volunteers for us. We take looking after them very seriously."
Senior Sergeant Shayne Wainhouse, of Whanganui Police, said the incident was reported just before 5pm on Thursday.
"An unknown female was going door to door in the Anzac Pde area but we haven't been able to identify that person," Mr Wainhouse said.
"We sent out a patrol but were unable to locate anyone."
Mr Crowe said emergency evacuations were led by the police and any doorknocking would have a police presence.
"There will be a uniformed presence with Red Cross, police or council and a police presence in the street. We will also have our stinger systems with a loudspeaker on the roof of a vehicle that plays at 160 decibels.
"This person who was knocking on doors was in a vehicle, not walking. We would have marked organisational vehicles on the street and we would be walking from door to door. People who are asked to evacuate should always ask for ID from the person who knocks on their door."
Mr Crowe said this week's weather event was a timely reminder for people to ensure they received emergency information from official channels.
"One thing that frequently happens when we have an event is that there are false stories that the bridges in Whanganui are closing.
"We hardly ever need to close the bridges in an emergency but if we did we would put a message out by all means we have, as soon as possible. Rumours of bridge closures cause a lot of angst for people.
"If you see it in a Facebook message, check with an official source to make sure the information is correct."
