The Prime Minister has expressed his deep shock at the “terrible attacks” in Vienna which have left three people dead and several injured.
Police in the Austrian capital said the attack was considered to have an Islamist motive, with a suspect – who was shot dead by police – armed with an assault rifle, carrying other handguns, and wearing a fake explosive belt.
Shots were fired at six different locations in the city centre on Monday evening and two men and one woman were killed.
Authorities are looking to determine if other attackers may be on the run.
Both Boris Johnson and Home Secretary Priti Patel tweeted to express solidarity with Austria after the deadly attack.
Mr Johnson said: “I am deeply shocked by the terrible attacks in Vienna tonight.
“The UK’s thoughts are with the people of Austria – we stand united with you against terror.”
Vienna police said several shots were fired shortly after 8pm local time in a city centre street.
Michael Ludwig, mayor of Vienna, said 15 people were admitted to hospital, seven with serious injuries.
A police officer was among the injured, Austrian police confirmed on Twitter.
Ms Patel said the UK, which has seen a number of terror atrocities in recent years, including an attack on Parliament in 2017, stood “ready to support” Austria following the shooting rampage.
The Home Secretary tweeted: “Deeply shocked and saddened by the incident that has taken place in Vienna this evening.
“My thoughts are with everyone who has been affected and we stand ready to support in any way we can.”
Vienna’s streets were reportedly particularly busy as people took to bars and restaurants on the eve of the introduction of harsher restrictions aimed at preventing the spread of Covid-19.
It is understood the UK will not choose to escalate its terror threat level before Wednesday, which will mark the eve of another lockdown across England.
The current threat level is set at “substantial” meaning an attack is likely.
The Prime Minister’s official spokesman told reporters the Vienna shootings were not discussed at Cabinet on Tuesday but that the Home Office had offered its counter-terror expertise to “help Austria with their investigation”.
Asked whether additional protections would be put in place on England’s streets before Wednesday, the Downing Street official said: “We are acutely aware of the threat that is posed by terrorism and our police and security services are always working around the clock to keep us safe.”
He said the terror alert level is “kept under constant review” when asked whether it would be raised following the recent atrocities in France and Austria.