MANKATO — Southern Minnesota residents are on edge after another quarry blast from a nearby mining operation sent a barrage of rocks through a neighborhood.

A blast at Jefferson Quarry sent chunks of limestone — some as large as bowling balls — flying into a Mankato neighborhood last week.

A large rock left a jagged hole just below a window of David Kreiselmeier’s house.

“I’m nervous,” he said. “Who’s to know whether you’ll come walking out the door one day and get blasted, or have a rock come through the window?”

According to a press release, the city has suspended the quarry’s blasting permit for the second time while it investigates. The quarry is owned by Jordan Sands, which produces frack sand for oil and gas extraction.

“I think we’d all like to get to the bottom of what transpired,” said Scott Sustacek, the company’s chief executive officer.

“Safety has always been our top priority. We’re conducting our own investigation and cooperating with the city’s investigation of this incident.”

The limestone and sand mining operation set off more than 4,500 pounds of explosives in April. The company said a 2.8 Richter scale earthquake occurred less than 10 seconds after the blast. It would be the first earthquake recorded in the city, according to the company’s consultant Barr Engineering Co.

U.S. Geological Survey scientists said it’s unlikely the tremors occurred naturally.

City and company officials said the quarry has considered closing at the end of the year, though it’s unclear if that will happen.