Greek authorities say ten people have been hospitalised with burns after allegedly being attacked with a caustic liquid in Athens.
The incident occurred during a meeting of senior church officials late Wednesday, officials say.
Seven senior members of Greece’s Orthodox Church were among those injured in the attack, allegedly carried out by a priest.
A police officer who helped restrain the suspect was also injured, as were a lawyer and a presiding clergyman.
They were transferred to state hospitals for treatment, and two clergymen were described as being in a more serious condition.
Police said it was not immediately clear what liquid was used, but added that the victims were being treated for burns.
The 37-year-old priest, who was facing the hearing for alleged drug-related offenses, was arrested unharmed and has been detained for questioning. The motive for the attack was not immediately clear.
"I express my disgust at this unprecedented event," Greek President Katerina Sakellaropoulou said on Twitter.
The country's health minister, Vassilis Kikilias, has visited an Athens hospital where the bishops were initially treated, joined by Archbishop Ieronymos, the leader of the Greek church.
Ieronymos told reporters he was "deeply saddened" by the attack but relieved that none of the injuries were considered by doctors to be life-threatening.
Health Minister Kikilias said four of the bishops were more lightly injured and were receiving first aid, while one was transferred to the plastic surgery unit of another hospital and the other two might also be transferred to other specialised units.