Granby - It took three explosive charges and an hour with a cutting torch to get inside the cab of an armored bulldozer that destroyed or damaged 13 buildings in this mountain town before grinding to a halt under a canopy of debris.

Inside, authorities found Marvin Heemeyer dead, apparently from a self-inflicted gunshot wound to the head. However, fearing Heemeyer had left them a postmortem booby trap, authorities waited hours before using a crane to gingerly remove his body Saturday morning from his self-styled, bulletproof cab.

While there were no leftover explosives, local officials looked with horror and awe upon the machine of destruction created by Heemeyer, a 52-year-old muffler-shop owner whose anger is thought to have been fueled by a zoning dispute with the town.

The virtual tank had cameras mounted outside and three video monitors mounted inside so Heemeyer could see where he was going. It had a .50-caliber gun on the front and two smaller-caliber semi-automatic weapons, one on each side, protruding through portals. It was equipped with an air conditioner, and its hydraulics were protected by armor. Its cab was reinforced with quarter- to half-inch metal plates, with a foot of concrete between them. Inside, there were a gas mask and two handguns, said Granby Mayor Edward Wang.

"It looks like something out of a Mad Max movie, but better done," Wang said. "It's eerie. And it's huge."

The destruction wrought Friday by the 13-foot-tall bulldozer was marked by a clearly discernible trail of white bite marks that the bulldozer's tracks etched into the black pavement - and by numerous spent bullet casings, their locations marked by yellow evidence tags. Despite having exchanged what one official estimated were hundreds of rounds of fire with Heemeyer, no one else was injured, which some considered nothing short of miraculous.

More incomprehensible still was the long-simmering anger that Heemeyer appeared to harbor. Many of the buildings he targeted had been connected in some way to people who played roles in a zoning decision that allowed a concrete batch plant to be built near his muffler shop on the outskirts of town, said Tom Hale, Granby's town manager.

On Saturday, several officials visited the metal shed where Heemeyer retrofitted the bulldozer. Though Heemeyer had sold the shed to a partnership including Bob Martin, owner of a local trash company, the new owners allowed Heemeyer to lease part of the shed for storage. Welding, Martin said, wasn't part of the agreement. And while Martin and his employees worked in the building every day, they never saw Heemeyer welding the bulldozer.

"He must have been working in there at night, because we're here early and we leave late most days," Martin said.

Martin said the lease was up June 1, and there have been inquiries from potential buyers. Observers think the impending loss of the shed's use may be why Heemeyer launched his attack last week.

Duane Dailey, chairman of the Grand County Board of Commissioners, speculated that Heemeyer used a ladder to climb up under a heavy, hinged door he had fashioned at the top of the bulldozer and perhaps propped open.

He dropped the door, Dailey said, and used the bulldozer to knock down the wall of the shed and begin his trek. Traveling at what one observer estimated was a top speed of 4 or 5 mph, Heemeyer headed for the concrete plant. Dailey said he tore into the side of the plant. Witnesses told Dailey that the plant's owner, Cody Docheff, cranked up a front loader, but failed to upend the bulldozer.

The Grand County Sheriff's Office released a statement Saturday saying that Heemeyer tried to "kill two state troopers who were hiding behind a concrete wall by pushing over the wall, however the troopers escaped."

Officers from the Sheriff's Office, the Colorado State Patrol and the U.S. Forest Service, among others, pursued Heemeyer, firing weapons, as he drove the bulldozer toward town.

The bulldozer proceeded through town, eventually hitting a dozen buildings and stopping in front of a propane company to fire numerous rounds from the .50-caliber Browning semi-automatic mounted at the front. The sheriff's news release said Heemeyer was aiming at electrical transformers and large propane tanks, which ultimately were not damaged.

Heemeyer doubled back and, as black smoke and fluid poured from the bulldozer, he headed for the Gambles of Granby hardware store, owned by a member of the town Board of Trustees that approved the concrete plant. Heemeyer repeatedly hit the store, and then became stuck. The engine stopped. Soon after, the sound of a muffled shot came from the vehicle.

That's when, authorities believe, Heemeyer shot himself.

"It looks like a single gunshot wound to the head," said Rodney Johnson, Grand County sheriff, after authorities gained access to the bulldozer. "There's a handgun laying on the floor."

On Saturday, Granby was inundated with offers to help rebuild, said Wang, the mayor.

"We have very good people in this community," Wang said. "The most gratifying part is, there are a lot of people who are lining up to help us rebuild.

"This town isn't going away," he said. "This is a setback. We're going to rebuild. This is a tough town."