"We are aware of a number of injured people, but at the moment we are not in a position to say how many or how serious."
Health minister Matt Hancock has said he hopes mass testing using faster COVID-19 tests can be rolled out towards the end of the year.
Among the dead were seven children, the youngest aged just eight, while 237 people were injured.
The man, claiming he was German, said that the student "looks like a Jew" and that "we should have f**king gassed the lot of you."
The sarsens were erected at Stonehenge around 2500 BC. The largest stands 30 feet (9.1 meters) tall. The heaviest weighs about 30 tons.
Khat is legal in Israel, but illegal abroad, leading to a massive wave of arrests abroad for Israelis coming to the country with khat on their persons.
Sky News said the stabbings took place at the site of Black Lives Matter protest in the town earlier in the day.
In 2014, a US military helicopter crashed on the coast of eastern England, killing all four crew on board.
This weekend, protests swept Europe in capital cities including Rome, Copenhagen, Budapest and Madrid and across Britain in solidarity with US protesters.
Shots were fired in Energen Close, Harlesden, Brent, at 2145 local time.