The Death Gun Salute was fired at 1pm on Friday in London, as well as at other locations around the UK and at saluting stations at home and abroad.
One round was fired every 10 seconds, with 96 rounds representing one round for every year of the Queen’s life.
Gun salutes took place in locations including Cardiff Castle, Edinburgh Castle, Hillsborough Castle, York, Portsmouth and Gibraltar.
In London, the King’s Troop Royal Horse Artillery fired the Death Gun Salute in Hyde Park, while at the same time the Death Gun Salute was fired at the Tower of London by the Honourable Artillery Company (HAC).
Some 71 horses made their way into Hyde Park, of which 36 pulled six First World War-era 13-pounder field guns.
The King’s Troop Royal Horse Artillery is a British Army mounted ceremonial unit that fires royal salutes on royal anniversaries and state occasions, such as state visits and royal birthdays.
The HAC dates its origins back to 1537, making it the oldest regiment in the British Army.
It took over the role of firing gun salutes from the Tower of London in 1924.
Major Matt Aldridge, Battery Commander, Honourable Artillery Company, said: “It has been an honour and privilege for the Honourable Artillery Company to have played our part in commemorating the life of Her Majesty The Queen, our Captain-General. In this period of national mourning, our thoughts are with the royal family.”
Salutes were also fired on six ships, one of which was in Portugal.
Gun salutes are customarily fired, both on land and at sea, as a sign of respect or welcome.
Gun salutes occur on royal anniversaries including Accession Day, the monarch’s birthday, Coronation Day, the monarch’s official birthday, the State Opening of Parliament, royal births and when a visiting head of state meets the monarch in London, Windsor or Edinburgh.
The Ministry of Defence (MoD) said the tradition of gun salutes routinely being fired throughout the country to mark significant national events dated back centuries.
Similar gun salutes were fired to mark the death of Queen Victoria in 1901 and Winston Churchill in 1965.