A police officer peeked around a makeshift barricade, looked a second time, and then opened fire.
Three bullets ripped through a paper target with the image of a knife-wielding man holding a child hostage.
These training exercises help police keep prepared as the nature of threats changes.
"What we do in training is what we do in real life," said Oro Valley Police Officer Kevin Mattocks, one of the department's certified firearms instructors.
A growing shortage of ammunition coupled with escalating costs means police need to plan for training exercises well in advance to maintain adequate stocks of ammunition.
"On average, we wait six to nine months to get ammunition from our distributors," said Oro Valley Police Officer Jodi Brackett. Brackett is responsible for ordering and maintaining a stockpile of ammunition for the Oro Valley police, and coordinates training operations.
For uniformity's sake, the department favors a select few calibers of handgun ammunition in addition to maintaining a cache of shotgun and rifle rounds.
These days, however, all but the most obscure calibers have grown scarce, even for police.
Like many agencies in southern Arizona, Oro Valley buys its ammunition from Douglas MacKinlay, who owns Diamondback Police Supply Company.
With 30 years in the gun business, MacKinlay said the scarcity of ammunition is unprecedented.
"I've never seen anything remotely like this," he said.
In the past, MacKinlay had no problems fulfilling law enforcement orders for 100,000 rounds of ammunition at a time in less than a month.
"Now it takes me six months to get 10,000 rounds," MacKinlay said.
He noted a recent instance where it took nearly a full year to fill an agency's order.
The long wait times have prompted some agencies to seek out supplies in unlikely places.
"We know of some agencies that have gone to Walmart," MacKinlay said.
He blames part of the problem on the intense demand for raw materials in places like China, where consumption of copper, lead and zinc has increased.
The increase of purchases from federal government agencies like the Department of Homeland Security and the effort to keep forces in Iraq and Afghanistan armed also has contributed to the shortage.
And those shortages have affected the civilian market for firearms and ammunition as well, with store shelves increasingly bare and customers scooping up in bulk all they ammo they can find.
MacKinlay, whose east Tucson store is open to the public, said he's long had a reputation for maintaining some of the largest stocks of ammunition in southern Arizona. These days he's having trouble keeping anything in stock.
"A week before the election our business doubled and it hasn't stopped," MacKinlay said. "Instead of buying a box of ammunition, people are buying a case."
The situation locally fairly mirrors a nationwide trend in gun and ammunition sales despite the best efforts of manufacturers.
"The demand for ammunition is fast outpacing supply," said Ted Novin of the National Shooting Sports Foundation. "The industry is operating at full capacity."
His group represents firearm and ammunition manufacturers and monitors gun sales.
The National Shooting Sports Foundation gauges firearm sales by reviewing data from the FBI National Instant Criminal Background Check System. Gun purchasers need to pass a background check before they can buy a firearm.
Reviews show that the number of background checks increased 42 percent in November 2008 from November 2007, Novin said.
The sales figures continued to swell in the early part of 2009 as well. Figures compiled by the group show an average 27 percent increase in background checks for the first three months of 2009 over the same time in 2008.
Novin said many people fear changes brought by the November elections brought would not bode well for gun owners.
"The increase in demand is attributable to the political climate," Novin said.
The spike in firearms sales has naturally fueled demand for ammunition, and prices have risen accordingly.
Novin said he wouldn't have definitive ammunition sales figures for a few months, when federal excise tax figures become available. But the anecdotal evidence suggests sales have soared — along with prices.
MacKinlay said that in the past most ammunition manufacturers raised prices annually. Now he sees price increases multiple times per year.
"In the last three years, we're seeing three to four price increases per year," MacKinlay said.
Those rolling increases have driven up the price of some of the most common ammunition like .223-caliber dramatically, from $75 per case to $200 per case.
Police agencies' prices are set in annual contracts with distributors like Diamondback. As such, their increases haven't been as rapid.
Still, Oro Valley police officials estimate that ammunition costs would likely grow by $8,000 in fiscal 2010 to more than $40,000 a year, if the department remains at status quo.
The department was paying $207 for a case of .45 caliber rounds. It now pays $229.
The same holds for rifle bullets that were $167 and now cost $181.
Despite the shortages and cost increase, Oro Valley police officials don't see the problem as a crisis.
"We're not at a panic point yet," Oro Valley Police Chief Danny Sharp said.
But the department has in the past had to buy rounds at retail prices from sporting goods stores to have enough for training exercises.
A recent Oro Valley police budget proposal would cut or shift about 15 percent of department spending. Included in that plan was a possible 25 percent cut to the department's field supplies budget, an area that includes ammunition and firearm costs.
Law enforcement officials say training reinforces their ability to react to situations and the evolving nature of threats.
"Before Columbine, there wasn't any training for school shootings," Mattocks said. School shooting and terrorist threats are examples of situations police routinely train for today that they never did in the past.
"We look at videos from the '70s and just laugh — if you did that now, you'd be dead," Mattocks said. "Police tactics and training have evolved."
Police departments across the state carry out similar training exercises at least twice a year as mandated by state laws, in addition to SWAT and other specialized instruction geared toward terrorism, school shootings and other threats.
Officers also have to target practice on a regular basis to maintain state standards. At each of those training sessions police expend ammunition on a massive scale — at times hundreds of rounds per officer.
"This is the basic of basics," Mattocks said. "Everything is built from this basic training."