Police forces in England and Wales have fined people for ignoring guidance to prevent the spread of coronavirus.
Martin Hewitt, head of the National Police Chief's Council, said the UK was in a "national emergency, not a national holiday" .
The NPCC said going to local beauty spots was not banned as long as there was no mingling.
Police chiefs say the vast majority of people are following social distancing measures to help protect the NHS.
In the first briefing from police chiefs since emergency legislation gave police powers to issue fines, Mr Hewitt also said:
- Anyone who was a victim of a crime and needed the police must still call for help
- All forces had developed contingency plans and the military was on standby for a worst-case scenario of police sickness
- Officers had now received comprehensive and clear guidance on using powers to encourage or force people to go home to prevent the virus spreading
- There were no plans for checkpoints to close beauty spots - but individuals and families needed to use their common sense
On Thursday, Derbyshire Police posted footage of couples and families walking alone in a remote beauty spot - triggering accusations that the force was over-reacting.
On Friday, the NPCC said that country walks were not banned under legislation that came into force on Thursday - nor was exercising more than once a day.
But police chiefs said the public needed to consider the risks to the NHS of spreading the virus through unintended social contact - and those could be increased by plans to go further than the local area.
"This is a national emergency, not a national holiday," said Mr Hewitt.
"The point is to try to avoid people contaminating others. We all saw the imagery from last weekend where open spaces were packed with people.
"Where we do not want to get to, as we approach a weekend, is places of natural beauty being absolutely packed with people coming and going in the same car park and the potential to spread the virus."
The new fines, introduced on Thursday, can be imposed on anyone who refuses to follow a police instruction to go home if they are in a gathering of more than two people - or conducting themselves in a way that will increase the likelihood of spreading the virus to others.
Deputy Chief Constable Sara Glen of Hampshire Police, who is leading the work around enforcement, confirmed in the briefing that forces had issued fines but no overall numbers were yet available.
"If individuals are in a group gathering and they don't take the request and the advice and the engagement from the officers to go home, and the only way we can secure compliance is to give them a fixed penalty ticket, that's what they would have been given for," she said.
"We want to know whether we're winning the kind of negotiation with the community to keep them in line with this regulation or whether or not we have a lot of people that are breaching it."
She said police would use a four-step approach: Engage with people and ask them why they are out, explain the risks they are posing to others, encouraging them to return home - and if they don't leave, enforce the law either through fines or even arrest.
Mr Hewitt added: "What we need is a common sense policing approach to stop the spread of the virus. That is what our police service is renowned for - being out there talking to communities."