Masked supporters of Nicaragua's government attacked a group of Roman Catholic priests led by Cardinal Leopoldo Brenes on Monday as they arrived to help anti-government protesters trapped inside a church.

Managua auxiliary Bishop Silvio Jose Baez sustained cuts to his arm as the delegation made its way into the San Sebastian Basilica in Diriamba south of the capital. The Episcopal Conference of Nicaragua posted photos of Baez's injured arm to its Twitter account with a message saying that pro-government "gangs awaited them, specifically to physically attack them."

The message continued: "Lord, forgive them for they know not what they do."

Dozens of government sympathizers chanting "Murderers!" and "We want peace!" and waving flags of the ruling Sandinista National Liberation Front roughed up the religious delegation. Some journalists covering the arrival were also attacked and had their equipment stolen.

The delegation succeeded in safely escorting out people who had been stuck in the church since police and armed pro-government allies violently put down a protest in the city Sunday. Human rights groups say at least eight civilians were killed and police said two of their own died in Sunday's clash.

Alvaro Leiva, director of the Nicaraguan Pro-Human Rights Association, who accompanied the delegation, said he was left speechless by the attack.

"Honestly, I never expected something like that would happen, a total disrespect," he said.

Tensions have been rising since the government announced cuts to social security in mid-April. The changes were quickly reversed, but daily street protests took on a wider call for President Daniel Ortega to step down. More than 250 people have been killed in violence.

On Saturday, Ortega announced that he would not move up elections scheduled for 2021.