LYON, France — French police interrogated one suspect and searched for others Sunday after a Greek Orthodox priest was shot and critically wounded while closing the door to his church in the French city of Lyon.

Investigators are trying to determine whether a man arrested Saturday night was the gunman behind the attack, or has information about it, according to a police official. The priest remains in critical condition after being shot with a hunting rifle, said the official, who was not authorized to be publicly named according to police policy.

The motive for Saturday’s shooting remains unclear. Anti-terrorism prosecutors are not investigating the case, and the Lyon prosecutor opened an attempted murder investigation.

The attack came as France is under high security alert after the killing of three people at a Nice church on Thursday, amid global tensions over cartoons of the Muslim Prophet Muhammad published in a French newspaper. The French prime minister has promised more protection for religious sites.

It also came amid tensions within the Greek Orthodox community in Lyon. The priest, a Greek citizen, had had a long-running legal dispute with a former monk who was convicted of defamation, according to French media reports.

The Greek Orthodox Holy Diocese of France identified the victim as Father Nikolaos Kakavelakis, and said he was scheduled to return soon to Greece after his time working at the Lyon church. “We pray for a speedy recovery and unequivocally condemn all forms of violence,” it said.

Antoine Callot, the pastor at another Greek Orthodox church in Lyon, told The Associated Press that the Greek Orthodox community in Lyon has not received any threats, but said he immediately asked police for security protection at his church after the shooting.