A student at an Indiana middle school barged into a class on Friday morning wielding two handguns and firing shots. A teacher and another student were wounded. The boy with the guns, the authorities say, was subdued, then arrested. And on a sunny day that began with the promise of a holiday weekend, yet another American city was left to cope with classroom bloodshed.

“Here we go again, and it’s just really, really, really unfortunate,” said Douglas G. Carter, the superintendent of the Indiana State Police. “I wish I had the answer.”

The shooting on Friday, at Noblesville West Middle School in suburban Indianapolis, came a week after 10 people were fatally shot at a high school in Santa Fe, Tex., an episode that revived a national debate about gun control and gun rights. It came nine days after a police officer in Illinois shot a gunman who interrupted a high school graduation rehearsal. And it came about three months after 17 people were massacred at a school in Parkland, Fla.

“We’ve had these shootings around the country — you just never think it could happen in Noblesville, Indiana,” Mayor John Ditslear said on Friday afternoon. “But it did. Our people were prepared.”