DUJIANGYAN, China — Angry parents whose children were killed in an earthquake-stricken school shouted “Oh, my child!” and “Tell us something!” when police forcefully removed them yesterday from a protest outside a courthouse.

The police action was the clearest signal yet that authorities are hardening their stance against the impromptu displays of public anger over the May 12 earthquake that collapsed schools and killed thousands of children.

The students’ deaths have become the focus for Chinese, both inside and outside the quake zone, fueling accusations about corruption in school construction. The brewing public anger has become a political challenge and threatens to turn popular sentiment against the authoritarian government as it copes with aiding millions displaced by the disaster.

Aggrieved parents and even rescuers have pointed to steel rods in broken concrete slabs that were thinner than a ballpoint pen among the 7,000 classrooms that were destroyed.

“Oh, my child!” one woman wailed as officers took the arms of the parents gathered outside the courthouse in this resort town. “Tell us something!” other parents shouted as they were led away. Their children had died in the Juyuan Middle School.

Journalists were then dragged up the courthouse steps by police — “For your safety!” they shouted. The journalists included an Associated Press reporter and two photographers who were held inside and questioned for a half-hour before being let go, after the protesters had been moved away.

The parents were forced along the sidewalk and out of sight. Surrounded by police at a side entrance to the courthouse, they tried to present what some described as a lawsuit, saying they had no other option because local officials weren’t responding.