Officials from the state police bomb squad and Bureau of Alcohol, Tobacco, Firearms and Explosives are preparing to detonate several live rounds of fireworks found after Sunday's two-alarm blaze near Maytown.
Vinegar Ferry Road is expected to remain closed from Route 441 to Martha Drive for about 30 minutes.
Susquehanna Regional police Lt. Stephen Englert said an ATF specialist on Monday will try to determine the cause of the fire that injured two people at 275 Vinegar Ferry Road near Maytown.
"Because of the extent of damage — it's making it difficult," Englert said. "There's not much left."
The fireworks fed multiple explosions that startled neighbors.
Englert said officials from ATF were summoned because explosives were involved.
As part of the investigation, Englert said police are trying to determine the roles of other people who were present at the time of the fire.
Englert also said a background check will be done on the property owner, Brian Bachman, to determine his employment history.
Bachman directed a fireworks show for the Maytown's 250th Anniversary celebration in 2010, according to Maytown's website.
The site also lists Bachman as being associated with Schaefer Pyrotechnics, Inc.
Including a location in Ronks, Schaefer Pyrotechnics serves Pennsylvania, Maryland, New Jersey, Delaware, Virginia and West Virginia, according to its website.
Bachman has been involved in pyrotechnics for about 30 years, according to Englert.
Englert said for the last few years, with the township's permission, Bachman has had a party and set off fireworks in a field near his residence. A show was scheduled for Oct. 11.
East Donegal Township manager Jeff Butler said Bachman has filled out an application to gain permission and the necessary insurance coverage to host a fireworks display.
Permits have been issued for fireworks displays at Bachman's residence since 2008, Butler said.
Butler added that Bachman applied for a permit for a display on Oct. 11.
Bachman's wife, Diane, was injured in the blaze.
Mrs. Bachman and a man, George Chronister III, of York, were taken by ambulance to Lancaster General Hospital.
Mrs. Bachman was treated and released, Englert said.
Chronister, 50, was transferred to the burn unit at Crozer-Chester Medical Center in Upland where he was listed in stable condition Monday morning.
His injuries were serious but didn't appear life-threatening, according to Englert.
Fire units were dispatched to the Bachman property just after 3 p.m. for what initially was reported as a barn fire involving multiple explosions.
An official arriving at the scene reported two burn victims lying in the grass and a three-acre field on fire. He also reported to county dispatchers that fireworks likely were stored in the building that was on fire.
The call was upgraded to a second alarm, drawing fire crews from about a dozen companies, including departments in York and Dauphin counties. About 30 pieces of fire apparatus were dispatched to the scene.
Crews knocked down the bulk of the fire within an hour, according to radio reports.
The garage and a nearby trailer were destroyed. At least two vehicles also caught fire.
Englert said Bachman had permits to possess what he called "commercial-grade" fireworks. "There was nothing illegal going on."
Some residents said they thought a plane crashed when they heard loud booms and felt the earth shake under their feet, then watched as plumes of heavy black smoke rose from a distance.
One man, who asked not to be identified, said he was in his backyard about a half-mile away when he heard a boom then saw a cloud of smoke, about 200 feet wide, begin to rise about 100 feet in the air.
His daughter said it was "like a volcano going up."
Bob Neiss, who lives nearby on Vinegar Ferry Road, said he jumped in his truck and drove to the Bachman home after hearing the explosions Sunday afternoon.
Regarding the injured, Neiss said, "The hand of God was on them."
Neiss said Bachman was always "very careful" in dealing with fireworks.
Other residents took to social media to report explosions so loud and violent that their houses shook. Some said smoke from the blaze could be seen from miles away.