SCARBOROUGH — Matt Linscott, of Biddeford, was like a kid in a candy store Friday, poring over cartons labeled “War of 1812,” “Vengeful Texan” and “Live Free or Die.”

“I’ve never seen so many fireworks in one place,” he said as he and his friends Jon Cross and Jaimee Austin tried to figure out what would give them, literally, the biggest bang for their buck among the offerings at Atlas Fireworks on U.S. Route 1.

Atlas, along with Phantom Fireworks at the Gateway Shoppes Plaza, was seeing a steady stream of customers with the approach of July 4th, the ultimate fireworks holiday. This is the first Independence Day since the 1940s when fireworks have been legal for all people over 21 to sell and ignite. Both shops opened this month, joining several others across the state.

Atlas, along with Phantom Fireworks at the Gateway Shoppes Plaza, was seeing a steady stream of customers with the approach of July 4th, the ultimate fireworks holiday. This is the first Independence Day since the 1940s when fireworks have been legal for all people over 21 to sell and ignite. Both shops opened this month, joining several others across the state.

The Legislature voted to legalize the sale and use of consumer fireworks in Maine, though many communities have regulated their sale and use.

While popular with many consumers, the new law has its critics and already has had some negative side effects.

Police report a jump in fireworks complaints and reports of shots being fired, which they attribute to fireworks. “We’ve had 12 complaints for the entire year. We had three the prior year,” Norway Police Chief Rob Frederico said. “It certainly appears that the majority of the complaints are coming from the in-town area, the more populated area.” In the past, he said, most fireworks were set off by summer residents at lakeside cottages. There were few complaints, and little police could do about it since the displays were invariably over before police could pinpoint their source.

“We’re certainly all hoping that it will be just the newness of the availability of them and that I would expect that come fall it will start to level off,” said Frederico, who said that Tuesday he is filming a public service announcement for local access television about local restrictions.

Some safety officials and health care workers will be holding their breath as the first big fireworks holiday arrives. Besides injuries, there are more fires reported on July 4 in the U.S. than any other date, and half are caused by fireworks, according to state officials.

“Even when they were outlawed in the state, we always were concerned because we knew a certain amount always came into the state. Now I’m afraid it’s going to be more of a free-for-all,” said John Dean, former state fire marshal. Dean was on record opposing efforts to allow sale and use of fireworks in the state; and as a member of Gov. Paul LePage’s administration, which favored lifting the ban, Dean was prohibited from testifying against the bill. Passage of the law by itself did not lead Dean to resign, but his decision was influenced by what he said was a campaign by the administration to roll back regulations which he felt were important.

“I’m still appalled they allowed this to happen. There’s no question, in the states where the consumer fireworks are more readily available, there are more injuries and more fires,” Dean said. “It’s all about money. I might say it’s blood money.”

Dean said the law won’t be changed until fireworks, which burn at more than 1,200 degrees, cause something drastic to happen or the child or grandchild of someone with influence is seriously injured.

“The profit they will make is probably much less than the cost of one serious injury to a child,” he said.

Mike Baumann, head of emergency medicine for Portland’s Maine Medical Center, said emergency room workers are bracing for the type of finger and eye injuries that have come in on past July 4 holidays, but doesn’t know whether having fireworks legal will lead to more problems.

“I think we see fireworks injuries whether they’re legal or not,” he said.

Scott Mitchell, manager at Atlas, said he pushes safety as much as anyone.

“The only way fireworks are going to stay legal and everybody has fun is if everyone keeps safe,” he said.

The industry insists that fireworks used responsibly are safe and cites numbers from the U.S. Consumer Products Safety Commission that it says show that fireworks injuries are down even though fireworks sales are up. Almost half of all fireworks-related injuries come from illegal or home-made explosives instead of the brand names sold in stores, they say. There were three fireworks-related deaths and 8,600 injuries nationwide in 2010, according to the U.S. Consumer Product Safety Commission.

One of the most important strategies for avoiding injuries is keeping the devices out of the hands of children, said Maine’s acting fire marshal, Joe Thomas. Thomas said his office is trying to educate people about the laws governing fireworks and about safe practices. The Pine Tree Burn Foundation funded the production of 5,000 brochures; and the state’s website, http://www.maine.gov/dps/fmo, has information about local ordinances, state restrictions and safety tips.

“It’s just incumbent on us to make it as safe as possible so people are not injured and property is not damaged,” he said. “There are many restrictions in the law itself, even before you put in local communities taking more restrictive actions through ordinance.”

Thomas has assigned one of his investigators full time to fireworks and explosives education and coordinating information about the new law. Restrictions range from the hours and dates fireworks can be used to prohibitions when the fire danger is class four or greater.

Most fireworks injuries occur to people 15 and younger, Dean said. Only people 21 or older are allowed to buy or detonate fireworks under the Maine law.

One factor that may keep the most powerful fireworks out of the hands of young people is the price. The big bangs don’t come cheap. For about $20, an adult can buy a Tiki Mon, a cylinder with glowing eyes and mouth, a fountain of colored flame meant to resemble hair, and almost no noise. Thirty dollars buys The Big Shamrock, which includes “willows” and “crackles” in the finale. Customers who want a bigger display, can go for the America’s Pride military-themed packages, which cost $349 but include more than 100 eruptions.

For those new customers who don’t know a “weeping willow” from a “fan” from a “peony,” an interactive touch screen allows them to see a video of what several of the popular products look like. Next to the screen is a printout of the state fire marshal’s list of municipalities that restrict fireworks — ranging from a complete ban to limits on the days and hours they can be used.

Mitchell said the fireworks available to consumers rival those that he detonates a pyrotechnic professional handling public displays such as those for municipalities.

“It gets you as close to being in the professional realm of pyrotechnics as you can be,” Mitchell said. He sells the same fireworks the company uses at what are called “close proximity” displays, when fans can be as close as 200 feet, such as at Portland Sea Dogs game.

He said fireworks have improved, with better and safer displays.

Mitchell’s not worried about losing jobs. For one thing, the professionals using an electronic ignition system can set off multiple fireworks in quick succession, faster than an amateur can.

Also, the law does not allow ordinary citizens to put on “public displays,” meaning shows that are open to the public to attend.

Mitchell said fireworks are a social activity.

“As enjoyable as they are, I know there are people who don’t like them. They’re noisy. But everyone who comes in here brings up family memories,” he said. “That’s what fireworks do. It brings people together. I think it’s really cool.”

“It’s a fun time for everyone to get together,” said Cross, one of the Biddeford shoppers. “It’s a good excuse to get together and set off some cool stuff.”

“I love the light shows,” said Brian Gonneville, of Saco, who was shopping for some pyrotechnics to celebrate his daughter’s high school graduation and 18th birthday.

Sharon Kimball, of Pownal, was collecting an armful of fireworks, selecting those with bright lights and fewer loud explosions. She’s fond of the Roman candles as long as nobody is foolish enough to try to hold it, she said.

In the past, she went to Seabrook, N.H., to buy fireworks, going in the spring to avoid the pre-July 4 crackdown at the Maine border, she said.

Customers say they’re not worried that legalizing fireworks will be harmful in the long run.