MOSCOW — A throng of thousands led by priests in black robes surged through police cordons in downtown Tbilisi, Georgia, on Friday and attacked a group of about 50 gay rights demonstrators.

Carrying banners reading “No to mental genocide” and “No to gays,” the masses of mostly young men began by hurling rocks and eggs at the gay rights demonstrators.

The police pushed most of the demonstrators onto yellow minibuses to evacuate them from the scene, but, the attackers swarmed the buses, trying to break the windows with metal gratings, trash cans, rocks and even fists.

At least 12 people were reported hospitalized, including three police officers and eight or nine of the gay rights marchers.

“They wanted to kill all of us,” said Irakli Vacharadze, the head of Identoba, the Tbilisi-based gay rights advocacy group that organized the rally.

Nino Bolkvadze, 35, a lawyer for the group who was among the marchers, said that if they had not been close to the buses when the violence began, “we would all have been corpses.”

Prime Minister Bidzina Ivanishvili of Georgia condemned the violence in a news release Friday evening, as the police urged the mobs to leave the city’s central avenue.

The attack comes amid an increase in antigay talk in Russia and Georgia, whose Orthodox churches are gaining political influence.

In a statement Wednesday, the leader of the Georgian Orthodox Church, Patriarch Ilia II, compared homosexuals to drug addicts and called the rally a “violation of the rights of the majority” of Georgians.

Conservative-minded Georgians traveled from other cities to condemn the gay rights demonstrators, and one told a television station that she had come to “treat their illness.”

“We are trying to protect our orthodoxy, not to let anyone to wipe their feet on our faith,” said Manana Okhanashvili, in a head scarf and long skirt. “We must not allow them to have a gay demonstration here.”

In a telephone interview, Mr. Vacharadze of Identoba said that priests from the Georgian Orthodox Church had led the charge that broke through a heavy police corridor.

“The priests entered, the priests broke the fences and the police didn’t stop them, because the priests are above the law in Georgia,” he said.

Ms. Bolkvadze, the lawyer with Identoba, speaking by telephone from a safe house in the city, said that despite promises from the police that there would be “unprecedented” protection for the rally, the riot police were unprepared.

“They didn’t have helmets,” she said. “They didn’t have the right equipment.”