Five monks were assaulted at a Vienna church on Thursday by two people, at least one of whom apparently demanded money and valuables, police said.

Police said the assault happened at about 1:30 p.m. at a complex in the city’s Floridsdorf district. No church service was underway when the assailants entered the Maria Immaculata church.

Police found the monks tied up, one of them with head injuries, nearly three hours later. They were aged between 56 and 68, and it appeared that the others had tried to intervene after one of the assailants — described as speaking with a foreign accent — attacked the oldest monk, the Austria Press Agency reported.

Police wrote on Twitter that, while the precise motive remains unclear, “a possible terror motive can be ruled out” in the incident at the Maria Immaculata church, The Associated Press reports.

Officers were searching for the perpetrators, including in the complex where the incident took place. They said Thursday evening that they had found nothing in the building.