MANAGUA, Nicaragua (AP) — Seventeen people who were arrested in previous anti-government protests were wounded in a prison disturbance in which a 57-year-old Nicaraguan-American dual national was shot dead, a lawyer for several inmates said Friday.

Attorney Yonarqui Martínez also said three student protest leaders were among those hurt, and alleged that Eddy Montes Praslin was shot in the back and "murdered."

"There is proof of this, no legitimate defense exists," Martínez said via Twitter.

Nicaraguan authorities have accused the inmates of causing "a serious disturbance" Thursday at La Modelo prison north of the capital, Managua. President Daniel Ortega's government reported Montes' death and said six prison workers had been injured, but did not say anything about inmates being hurt.

Worried family members gathered outside La Modelo on Friday seeking information about their loved ones.

"They tell us everything is calm, but we cannot believe that when there was a death," said Jacqueline Valdivia, mother of student leader Nahiroby Olivas, one of those listed as wounded.

Authorities later allowed a group of mothers inside. Emerging they described finding their sons bruised, wounded and broken, and said they had not been hospitalized.

"All the boys are totally wrecked," said Yesenia Estrada, the mother of Byron Corea Estrada, another student leader. Estrada alleged that guards used not only bullets but rifle bayonets against the prisoners.

The government has said prisoners rushed guards inside the facility and struggled with one of them "with clear intentions of taking away his service weapon," and Montes was shot in the melee.

Contradicting that account, Valdivia said the disturbance started when guards insulted several prisoners in the recreation yard. In the exchange of words, a guard fired from a tower which led others to attack the prisoners, she said.

Corporacion radio, a station critical of Ortega's government, said four people were in serious condition from gunshot wounds and attributed the injuries to armed police and guards.

Corporacion published photos apparently taken in the prison yard showing bandaged men with bruises, welts, black eyes and cuts on the head, face, arms and back, as well as spent shell casings and used tear gas canisters.

Martínez said the disturbance took place in a section of La Modelo that holds hundreds of people whom the opposition and human rights groups say are political prisoners who were arrested for opposing the government. Ortega officials allege that opposition protests were tantamount to an attempted coup and have called the demonstrators "terrorists."

The International Committee of the Red Cross, which had personnel inside the lockup at the time, confirmed the existence of wounded prisoners but has offered few details about what happened. The ICRC said that prison officials had asked it to mediate a problematic situation in several cellblocks, and that it had facilitated the exit of wounded prisoners who were treated by prison medical staff.

Montes, a U.S. citizen, was arrested last November and accused of terrorism, aggravated robbery, illegal possession of weapons and disruption of public order. According to Nicaraguan local media, authorities alleged he had looted a police clinic and robbed and burned city hall in the northern city of Matagalpa.

La Prensa newspaper said Montes was known to fellow prisoners as "the pastor" for performing nighttime religious services.

The U.S. Embassy in Managua said via Twitter that Washington condemned the use of lethal force against him. It expressed condolences to his family and urged a full investigation into "the circumstances of this tragic incident."

Ramón Jáuregui, chief of a European Parliament delegation that visited Nicaragua in March, tweeted that the government "must clear up the events without lies."

The United Nations' human rights office expressed regret and urged authorities to carry out an exhaustive probe of the incident.

Some young people staged a small protest on property of the Managua Cathedral; police deployed patrols and riot officers around the area.

The incident is the latest chapter in over a year of political crisis.

Protests against social security reforms began in April 2018 and grew in intensity and scope to demand Ortega's exit from office and early elections. The demonstrations were put down forcibly by security forces and armed, pro-government militias, with at least 325 people killed in the crackdown, more than 2,000 wounded and over 52,000 who fled the country, according to the Inter-American Commission on Human Rights.

The government and the opposition opened talks on resolving the crisis in February, but those have stalled and there has been little consensus on issues such as the release of jailed protesters.