Following an apparent terrorist attack aboard an underground train in London, British Jews said that their nation’s determination to “defeat extremists” is only strengthened by the incident.

The statement by the president of the Board of Deputies of British Jews, Jonathan Arkush, followed reports of an explosion at the Parsons Green Station in London on Friday morning.

Several people were injured in the blast, which police are treating as a terrorist attack, Sky News reported.

“Our thoughts go out to all of those injured in the terrorist attack on a train at this morning,” Arkush wrote in the statement. “The more the extremists attempt to disrupt our lives and challenge our values of tolerance and mutual respect, the stronger our resolve and determination to defeat them.”

The Community Security Trust (CST) confirmed they had spoken with the Metropolitan Police. They wrote on Twitter: “#ParsonsGreen now declared terrorist incident. We urge community to be alert, report anything suspicious & follow CST for further updates.”

In a security bulletin, they said: “Police are treating as a “terrorist incident” this morning’s explosion on an underground train at Parsons Green station, west London.”

“CST has spoken with Police and we have been assured that at this stage there is no evidence that the explosion has any connection to the Jewish community. Nevertheless, given the current high terror threat level and the potential for attacks against multiple targets, including against the Jewish community, we urge everybody to be vigilant, to report anything suspicious and to follow all security protocols and instructions if you are visiting a Jewish location.”

They urge alertness over suspicious bags, packages, people or vehicles.

Israeli Prime Minister Benjamin Netanyahu tweeted after the incident, saying: “We stand with PM May and the people of Britain in our common fight against the forces of terror.”

The explosion occurred at about 8:20 a.m. local time at the height of rush hour on a busy commuter line into central London.

Sylvain Pennec, a software developer from the London area took images of a suspected explosive device that is believed to have caused the blast. “I heard a boom and when I looked there were flames all around,” he told Sky News.

“People started to run but we were lucky to be stopping at Parsons Green as the door started to open. He described what “looked like a bucket of mayonnaise”, adding: “I’m not sure if it was a chemical reaction or something else, but it looked home-made.”

London mayor Sadiq Khan said in a statement: “The Metropolitan Police have confirmed that the explosion on a train at Parsons Green Station this morning is being treated as terrorism. Our city utterly condemns the hideous individuals who attempt to use terror to harm us and destroy our way of life. As London has proven again and again, we will never be intimidated or defeated by terrorism.”