A mother and son who died after a rescue operation at Aberdeen beach have been named by police.

Julie Walker, 37, and Lucas Walker, six, from Aberdeen, were part of a group who got into difficulties in the water on Saturday afternoon.

Emergency services were called at around 4.45pm and a major operation was launched, with five people pulled from the water and taken to Aberdeen Royal Infirmary.

Ms Walker and Lucas, understood to be mother and son, later died in hospital.

Lucas's brother, Samuel, "bravely" entered the water in an attempt to save his mother and brother and is making a "steady recovery" in hospital, police said.

A 25-year-old woman and 28-year-old man were also taken to hospital, but have since been discharged.

The "heroic attempts" by emergency services and members of the public to save the group while facing "treacherous sea conditions" have been hailed by police.

Chief Superintendent Campbell Thomson, north east divisional commander, said: "This is a very tragic incident and our thoughts are with the Walker family at this sad and difficult time.

"Whilst officers continue to investigate the circumstances of the incident, it is clear heroic attempts were made to save Julie and Lucas by both on and off-duty police officers, emergency service personnel and members of the public, facing treacherous sea conditions and high winds during their rescue bid. Their brave efforts cannot be overstated."

He added: "I'd like to pay special tribute to Lucas's brother Samuel, who very bravely entered the water in an attempt to rescue his mother and brother. We are all very thankful Samuel is making a steady recovery in hospital."

Onlookers described the deaths as "heartbreaking" and "devastating".

Emma Anderson, 25, who was visiting the beach with her family, told the Sun on Sunday newspaper: "I saw what looked like a small child floating in the water - I am absolutely devastated."

Rachel McBain, 25, who rang 999, told the Sunday Mail newspaper she saw two children go into the waves.

"I turned away for a few minutes and when I looked back I saw the two bodies floating in the water," she said.

"I was panicking but phoned the police. The next minute it was absolute chaos and there were sirens within seconds."

Writing on Facebook, onlooker Stacie McPherson said the incident was "absolutely heartbreaking".

Scotland's First Minister Nicola Sturgeon was also among those paying tribute. She tweeted: "Tragic, heartbreaking news. My thoughts are with all those involved."

Aberdeen Central MSP Kevin Stewart posted: "Sorry to hear of the tragic event that has taken place at Aberdeen beach. My thoughts are with those involved, their families and friends."

Chief Supt Thomson warned members of the public to take care near water.

"Our seas can be extremely unforgiving - even during the summer months - with conditions changing rapidly. I would urge people to be extremely careful when near any body of water whether you're swimming, sailing or walking near the water's edge," he said.