MARINETTE, Wis. – For about two hours, no one at Marinette High School knew Sam Hengel was holding his social studies class hostage with two pistols and a bag stuffed with a pair of knives and more than 200 rounds of spare ammunition.

Although only Hengel was harmed in the standoff, fatally shooting himself as police stormed the room, students questioned the lag time in the response and whether security should be upgraded as they returned to class Wednesday after a day off.

“They should be aware when things go wrong or something,” said sophomore Ricardo Jaimes.

Hengel started the standoff by firing three shots in front of more than two dozen students in teacher Valerie Burd’s class, blasting a hole in the wall and tearing apart a movie projector. But no one else realized anything was wrong until after the school day ended, when the principal unlocked the classroom door and found himself looking down the barrel of Hengel’s gun.

The incident shook this city of 12,000 people bordering Michigan’s Upper Peninsula, and students and parents wondered how Hengel could have gone undetected for so long, especially after he fired three shots. Marinette Police Chief Jeff Skorik said students walked by the classroom as usual, completely unaware Burd’s class was in danger.

“I was just wondering where the cops were and when we were going to get out of this,” said Austin Biehl, a sophomore who was held hostage in the classroom.

Hengel’s motive remains unknown. Students said he never hinted at what might have been bothering him but didn’t threaten any of them and didn’t appear to want to shoot anyone.

The sheer number of bullets suggests he was prepared to injure a large number of people, but Skorik declined Wednesday to draw any conclusions. He said investigators don’t know whether the guns may have always been kept in the bag with the ammunition or whether Hengel put it all together specifically for the standoff.

Investigators are still piecing together a final report on the incident, but Skorik said no one identified the sounds of the first shots as gunfire.

Burd had a lot of high-tech video equipment in her room and was playing a movie when Hengel returned to class, which may have dampened the noise, Principal Corry Lambie said. School Board President Scott VandeHei said students outside the classroom may have assumed the sound was a desk turning over.

“From what I’ve heard, it’s not that hard to see how that could happen,” VandeHei said.

Lambie acknowledged library staff missed Burd when her seventh-hour class showed up without her but that it wasn’t unusual for her classes to visit the library, and the students were supervised.

Skorik pointed out Burd’s sixth-hour class doesn’t move from period to period en masse, so seventh-hour teachers likely would not miss one or two students who fail to show up.

“A student here or there could be skipping or get sick,” the police chief said. “That really wouldn’t be identified as a serious matter by any particular teacher.”

Skorik said law enforcement’s response was excellent, noting police held a school shooter exercise in August at Marinette High. Burd issued a statement late Tuesday saying she thought the response was handled “appropriately under the circumstances.”

School officials have promised to re-evaluate their emergency procedures. Debate already has begun about whether metal detectors are the answer.

“Maybe,” said Kody Baumler, 16, one of Hengel’s friends. “Or something to make sure this wouldn’t happen. One of my friends died.”