British Prime Minister Keir Starmer flew home early from a summit of European leaders in Copenhagen after an attack outside a synagogue Thursday in northern England.

Starmer said he was appalled by the attack and additional police officers would be deployed at synagogues across the UK.

An assailant drove a car into people outside a synagogue in Manchester and then began stabbing them, killing two and seriously wounding three in a terrorist attack on the holiest day of the Jewish year, police said.

Officers shot and killed the suspect, Greater Manchester Police said, though it took authorities some time to confirm he was dead because of concerns he had an explosive on him.

The Metropolitan Police in London, who lead counter-terror policing operations, declared the assault a terrorist attack.

Assistant Commissioner Laurence Taylor said two other suspects were arrested, though he provided no further information on the arrests.

The attack took place as people gathered at an Orthodox synagogue in suburban neighborhood of Manchester on Yom Kippur, the day of atonement and the most solemn day in the Jewish calendar.