Essex police have insisted they are not “crying wolf” in urging residents in the coastal communities of Jaywick, Mistley and West Mersea to evacuate their homes immediately before expected severe flooding on Friday night.

By early afternoon evacuees were beginning to arrive at emergency “rest centres” in Clacton and West Mersea.

Ch Insp Russ Cole confirmed a full evacuation was now under way. Speaking to the Guardian at a rest centre where more than 75 people had registered by early afternoon, Cole said the force was not “crying wolf”.

A severe flood warning is in place for Jaywick, Mistley and West Mersea at high tide, expected at 12:15am. A full evacuation plan was triggered at about 11am on Friday.

Police had expected the biggest flood risk of the day to come at high tide at lunch time, but high tide this evening is now seen to be a higher risk with coastal flooding a “real and present risk”, Cole said.

The evacuation of seaside village Jaywick started on Thursday night but was put on hold by mid-morning while police waited for assessments from the Environment Agency. That evacuation was “reinvigorated” by 11am and by early afternoon about 200 officers were knocking on doors urging people to leave Jaywick.

A rest centre with inflatable beds, sleeping bags and hot food has been set up at Tendring Education Centre, Jaywick Lane, Clacton, for Jaywick and Mistley residents.

Mersea residents were being directed to the Mica Centre in West Mersea “until their homes were safe to return to”.

Michelle Hudson and her dogs Alfie and Henry walk along a street in Jaywick from where police are evacuating residents. Photograph: John Stillwell/PA

“We haven’t taken this decision lightly,” said Cole. “We are not crying wolf we have taken a carefully considered assessment. We can’t force people to leave their homes but there is a real and present risk.”

Some residents facing evacuation have expressed concerns about looting, but Cole said there would be increased police patrols around empty properties.

“If anyone thinks they can come with a van and commit crime in any of these areas they are wrong. We are doing stop checks and criminals are more likely to be arrested today when there are 200 extra officers on the ground.”

To those who chose not to evacuate the town, he said: “If you are contacted by police please do listen, they are saying this for a reason. Stay with friends or family or come to the rest centre with your pets – there really is no reason to stay behind.”

IT manager Darren Clegg was facing his second night at the Tendring rest centre, after being evacuated from the nearby St Osyth’s beach caravan park on Thursday night.

He said he was told he did not have to be evacuated but was left with the impression that people who did not leave would be penalised.

Because he had had a glass of wine he could not drive, so walked three miles to pick up his car on Friday. When he arrived the caravan park was shut and he could not retrieve it, so he hitchhiked back to the centre.

“I’m OK with spending another night here,” he said, adding that tonight he was going to try to avoid the snoring man who had kept him awake the night before.

“We’ve been very well looked after, there is food and tea and coffee, we have mattresses and sleeping bags so I can’t complain.”

Barry Dawson, 66, and Brenda Horwood, 74, went to the rest centre in the hope of getting more information.

The couple were worried about their bungalow in Jaywick, which they have just finished renovating after 16 months.

Police had not yet called on them or posted an information leaflet, they said.

“My nan and grandad were floating around on an upturned table on Canvey Island in 1953 so we’re not going to take any risks,” said Dawson. He called the information they had been given “abysmal”.

“We’re alright, we’ve got the van and I’m a bit of a Boy Scout but the old people on our street, they can’t get out on their own. I’ve asked people here for information but they can’t tell me if my house is in the red zone or even when high tide is.”

Nigel Brown, communications manager for Tendring district council, said the council and police were doing everything possible to keep people informed.

The rest centre was expecting greater numbers of evacuees as the afternoon progressed and people became more nervous as darkness approached.

“It is one thing if a flood happens during the day, but at night it could be much worse. That is why we are asking and helping people to come now, especially the elderly, frail and people on their own.”

Transport, which had been paused this morning, is now available to bring people to the rest centres, he said.