A man in his seventies has been stabbed at London Central Mosque by London's Regent's Park.
He has been assessed in hospital and his condition is not life-threatening. It is not being treated as terror related.
A 29-year-old man, who is believed to have been attending prayers, was arrested inside the mosque on suspicion of attempted murder. He has been taken into custody at a central London police station.
Father Stephen Evans, priest at St Marylebone Parish Church, a short walk away from the mosque, told Premier: "I'm very saddened by it. I know the mosque well - those who are the leaders there and my prayers and sympathies go out to all at the Islamic and cultural centre this afternoon, especially to the director general Dr Ahmad Al Dubayan and his team and our prayers are with very much the person who's been stabbed and his family."
He explained that St Marylebone Parish Church has good relations with the Muslim community across the park from them, saying: "The mosque hosts an interfaith gathering called Pathways, which brings together the Christian, the Jewish and the Islamic leaders here in central London. So it's a place that I know well."
The man stabbed at London Central Mosque was calling worshippers to prayer, a statement on the mosque's website said.
It read: "There was an incident today at London Central Mosque where an unknown individual attacked and stabbed the Muazzin (the person who makes the call to prayer) during Asr Prayer around 3pm.
"The attacker was apprehended by the worshippers until the police arrived and arrested him.
"The Muazzin did not sustain any life threatening injuries but was seriously injured and is being treated at the hospital. We will provide further updates.
"We await further information from the police regarding the incident, our thoughts and prayers are with the Muazzin and his family."
Fr Stephen encouraged people to pray for those affected: "
People need to hold - not just the community - but those who think of the Central Mosque as their home in their thoughts and their prayers and also everybody who may feel very threatened or very vulnerable when an event like this happens which seems to tear at the day heart of a free and open and liberal democracy.
"I think we all have to be both vigilant, but also aware of the world around us and some of the awful things that happen, sadly, in the name of religion, or against religion, I think it works both ways."