LONDON (AP) — British police arrested two men on Wednesday in connection with an arson attack on four ambulances belonging to a Jewish charity, which authorities are investigating as an antisemitic hate crime.

The Metropolitan Police said the two men, aged 45 and 47, were arrested on suspicion of arson with intent to endanger life and both men have been taken to a London police station for questioning.

Commander Helen Flanagan, head of Counter Terrorism Policing London, said the arrests marked “an important breakthrough in the investigation.” But she noted that surveillance camera footage of the incident suggests three people were involved.

Police have not declared the incident to be a terror attack, but are investigating a claim of responsibility by a group with potential links to Iran.

The blaze early on Monday morning in Golders Green, a London neighborhood with a large Jewish population, consumed four ambulances belonging to the volunteer organization Hatzola Northwest. Oxygen cylinders on the vehicles exploded, breaking windows in an adjacent apartment block.

Also shattered was the community’s shaky sense of security, already strained by wars in the Middle East and what many say is soaring hatred of Jews.