Gunmen opened fire on a barricade manned by anti-government protesters, killing a student, amid stalled efforts to revive peace negotiations between the government and opposition.

Roman Catholic bishops came away from a meeting late Thursday with President Daniel Ortega without a formal plan to return to the negotiating table.

Meanwhile, the Nicaraguan Center for Human Rights said 19-year-old student Cesar Chavarria became the 135th person to die in anti-government protests that have flared since April 18.

A student leader said Chavarria was killed and another student was wounded overnight Thursday to Friday when armed men in vans opened fire on a barricade near the National Autonomous University in Managua.

State broadcaster Radio Nicaragua was targeted in a firebomb attack early Friday, the official government website reported, charging that the arson was "organized and paid for by the right".

The Nicaraguan Episcopal Conference (CEN) said the bishops had presented "the pain and anguish of people who have suffered in recent weeks" during a "frank and sincere meeting" with Ortega.

It did not elaborate on the details of the bishops' proposal, but said it "reflects the feelings of many sectors of Nicaraguan society" and was awaiting a reaction from Ortega.

Silvio Jose Baez, the auxiliary bishop of Managua, said Ortega "asked us for a period of reflection to give us an answer, which we asked he give us in writing" -- after which they will consider the feasibility of renewed negotiations.

Bishops had called off the talks last week after 16 people were killed in a crackdown by security forces on a protest led by mothers of victims of the unrest.

Costa Rica announced Friday it would provide visas to relatives of diplomats accredited in Nicaragua who want to leave.

"We have decided to provide them with diplomatic courtesy visas so that, as a result of the crisis situation in Nicaragua, the relatives of the diplomats can come" to Costa Rica, said Foreign Minister Epsy Campbell.