Three people have died and at least 21 more were injured after a homemade bomb carried by a woman exploded near a central Moscow restaurant on Saturday evening, Russian authorities said.

The explosion, which occurred at around 7.55pm local time (5.55pm BST), detonated near an upscale Italian restaurant located in one of Moscow’s seven Stalin-era skyscrapers at Kudrinkskaya Square, police said.

Russia’s Anti-Terrorism Committee said that an unidentified woman had tried to get ​into ⁠the restaurant, but was ‌stopped by a security guard, according to Russian news agencies.

Among the dead were the security guard, the woman, and another visitor, the committee added. They have not been named and there are no official theories about the perpetrator. Those injured had received wounds of varying seriousness, according to police.

The Kommersant daily newspaper cited sources who claimed that the bomb had been intended to maim and kill guests who were enjoying themselves outside on the restaurant’s summer terrace. The restaurant’s ‌website said the venue had ​been closed on Saturday for a private event, but it is unclear who was present.

More than four years into a full-scale war with Ukraine, Russia’s FSB security service said earlier this year that authorities would step up protection for high-ranking military officials after a series of assassinations and attempted killings which it blamed on Kyiv.

In June, Vladimir Putin’s ammunition chief Damir Davydov was killed in a car bombing in Moscow.

But there has not yet been any suggestion that Saturday’s attack was linked to the Ukraine war, with Kremlin officials still to put forward any theories.

Russia’s state RIA news agency released video of heavily armed law enforcement officers at the scene, which was closed off from the public.

Russian state TV earlier speculated that the explosion may have been caused by a gas canister detonating, a theory which was later dropped.

Investigators and emergency services remain working at the scene.

The Baza online news outlet, which has good contacts with law enforcement, said the explosion had occurred at the upscale Balzi Rossi Italian restaurant.