Police have warned people to stick to coronavirus rules after large crowds were seen brawling and drinking in a city park on the day restrictions eased.
Videos shared on social media showed some hugging and others pushing and shoving at Nottingham Arboretum.
One local resident described the scenes as "horrendous".
Extra police patrols are being planned to prevent similar scenes over the next few days.
Since Monday morning, two households or groups of up to six people have been allowed to meet outside in England.
IMAGE COPYRIGHTASHLEY KIRK
image captionPolice believe the warm weather brought more people out
Footage appeared to show multiple instances of social distancing being ignored as large numbers began gathering from the afternoon and stayed into the evening.
One video showed people pushing and shoving each other and a large amount of litter was left behind.
"Last night it was horrendous seeing what was going on," the resident told BBC Radio Nottingham.
"I walked past on the way to the shop and it was just madness. It seems like a real joke when people are still struggling.
"Staying late, leaving all this rubbish. Every single element of it is completely selfish."
The most recent figures show Nottingham had a coronavirus infection rate of 74.5 per 100,000 people in the week up to 21 March - higher than the national average.
For a period in October, the city also had the highest infection rate in the UK.
image captionOverflowing bins and discarded litter were seen on Tuesday morning
Insp Paul Molloy said: "While we can of course understand people's desire to want to be out in the sun and enjoy these mild temperatures we are currently experiencing, the government and our health colleagues remain extremely cautious and advise that people continue to minimise social contact.
"We would like to remind people that we are still only partly out of lockdown measures.
"We are aware of a number of residents choosing to be out in the Arboretum... and our officers are now engaging with people to ensure they are still sticking to the rules.
"It is up to us all to keep to the measures so we can continue on the roadmap out of lockdown, by keeping the virus at bay."
IMAGE COPYRIGHTNOTTINGHAM CITY COUNCIL
image captionSigns have been added warning people alcohol is forbidden at the park
Nottingham City Council leader David Mellen blamed a "selfish minority" for the "extremely disappointing" scenes.
"We have all made sacrifices over the last year to keep each other safe," he said.
"Over 600 local people have died due to the virus.
"We have had discussions with senior police officers and there will be increased presence in our parks.
"Drinking alcohol in public spaces is not permitted in Nottingham and will be seized on entry to our parks today."