Several Chinese journalists have said in recent days that officials from the central government told their news organizations not to continue reporting on the issue of unsafe schools. Here in Dujiangyan, the police and soldiers have cordoned off the sites of collapsed schools and are turning reporters away.

The protest on Tuesday morning took place outside a five-story courthouse on a wide boulevard in central Dujiangyan. It was organized by parents who lost their children in the collapse of Juyuan Middle School, in a suburb. Most of the school’s 900 students were killed in a deluge of bricks and concrete, even though buildings around the school remained largely intact. Rescue workers and soldiers scoured the rubble for days afterward, but few survivors were pulled out.

Calls seeking comment on Tuesday’s protest, made to the courthouse, petition office and city government headquarters here, were not answered.

Government intimidation of the parents organizing the protest began as early as the previous night, Ms. Li, a participant in the protest, said in an interview. Ms. Li, who lost a 14-year-old daughter in the Juyuan collapse, agreed to speak on the condition that only her last name be used, for fear of government retribution.

Officials in Juyuan visited with seven leaders among the parents on Monday night and persuaded six of them not to attend the Tuesday rally, Ms. Li said. The visits came after parents carried out a protest earlier that day demanding that Juyuan officials apologize for not pushing rescue workers to keep searching for the bodies of children classified as missing.

But the protest took place anyway. It started at 8 a.m. When the parents reached the courthouse, they were confronted by police officers in black caps and uniforms. A handful of reporters who were on the scene were taken by the police into the courthouse against their will, according to Ms. Li and a firsthand account by a reporter for The Associated Press.