Police in Co Armagh have warned young people about the dangers of swimming in disused quarries following reports of crowds gathering at them.
On Tuesday night, a group was spotted by a member of the public at Navan Fort quarry, just outside Armagh City, the scene of four drownings in the past 24 years.
Sinn Fein councillor Brona Haughey said the "concerned woman" had contacted them and they in turn had notified police.
A PSNI spokesperson confirmed they had received a report that a large number of youths were swimming in the quarry.
"The report was received just before 10.40pm. Officers attended, but there was no one there at that time," the spokesperson said.
"Police are keen to stress that quarries are extremely dangerous and should be avoided. Officers will be patrolling this area."
The last person to die in the quarry was 20-year-old Brendan Bell who got into difficulties while swimming in April 2010.
The first victim was father-of-three Roy McGinley who drowned in June 1996, followed by Christopher Connolly in May 2000 and John Basketfield who drowned in February 2005.
In a Facebook post, police said quarries posed a number of safety risks including extremely cold water which can affect heart rate "and could cause death within seconds" as well as risks from submerged machinery and debris, possible chemicals, rubbish and dead animals.
David Walker, leisure safety manager at the Royal Society for the Prevention of Accidents, also warned of cold water shock.
"Even on a hot day, the water will be a lot colder than you were expecting and can lead to cold water shock, which is when sudden immersion makes you gasp and breathe in water, and this can easily lead to drowning," he said. "This can affect even the most experienced swimmers.
"I would urge parents to speak to their children about the potential dangers of open water, especially during the hot weather.
"Cold water shock is the key danger to understand as it is the reason why many people drown at this time of year. It also puts the lives of rescuers in danger."