A 20-year-old Bowie man has admitted to setting off “bottle bombs” at six crowded movie theaters across the region, authorities said, but they declined to say what motivated the attacks, which sowed chaos and fears of gunfire.

Manuel Joyner-Bell Jr. allegedly created improvised explosive devices by mixing acid and metal in Mountain Dew and Lipton Brisk bottles and deployed them during showings in Virginia and Maryland the past three months.

Authorities said he used Twitter to update followers about media coverage of the incidents. Court records and interviews with neighbors painted a portrait of a troubled young man who was occasionally alleged to be violent.

Police and fire officials said at a Monday afternoon news conference that the bottle bombings were much more than pranks — and the at least 18 charges he faces so far reflect that. Joyner-Bell could face decades of imprisonment if convicted on all counts of using destructive devices. His bond was initially set at $50 million before being changed to no bond.

“The national capital region police and fire departments are always on a heightened state of alert, but in the last three weeks, they’ve been on a really heightened state of alert as the insidious acts of bottle bombs being thrown into movie theaters across the region created panic, mayhem and, frankly, endangered the lives of thousands of people in the region,” said Marc S. Bashoor, chief of the Prince George’s County Fire/EMS Department.

The home where alleged bottle bomber Manuel Joyner lived with family. The house number was covered in duct tape Monday. (Justin Jouvenal/The Washington Post)

Joyner-Bell’s attorney, Warren Price, said his client, a high school graduate with a full-time job, is “presumed innocent.” But he also said authorities are overstating the seriousness of the incidents.

“Whoever is guilty of these charges was committing a high school prank,” Price said. “This seems like election year overcharging. This is more akin to someone placing a cherry bomb in a mailbox than a terrorist-level attack.”

The first attack occurred March 10, and they continued until late May, including one during a May 24 showing of “X-Men: Days of Future Past” at the Magic Johnson Theater in Largo. During that incident, which occurred about 1:40 a.m., a witness saw someone’s arm hurl a bottle over a wall, shortly before an explosion occurred in theater 11, according to charging documents. The theater was quickly evacuated, and no one was injured.

Investigators found a 1-liter Lipton Brisk bottle between the fourth and fifth row of the theater and the cap in front of the movie screen, charging documents show. The bottle was over-pressurized by mixing muriatic and gluconic acid — commonly used in cleaning and for industrial uses — with metal foil, according to charging documents.

The other incidents occurred in Fairfax, Anne Arundel and Montgomery counties and the City of Alexandria. The fear they created was captured vividly in emergency calls released by Fairfax County authorities.

Moviegoers reported hearing pops, like a gun being fired, and then desperately fled for the exits during a showing of “Godzilla.” Some cowered in the mall’s bathroom. “There is a gunshot, please please!” one caller pleads with a dispatcher, nearly in tears.

Authorities said it was lucky no one suffered more than minor injuries in any of the incidents.

Manuel Joyner, 20, was arrested by officials from the Prince George's County Office of the Fire Marshal. (Courtesy of Prince George's County Office of the Fire Marshal)

“This actually could have been deadly, if not from the effects of the bottle bombs, from the potential stampeded of people,” Bashoor said.

Authorities said Joyner-Bell was the only person to have bought a ticket for all venues on the days of the detonations, according to charging documents. He also “liked” a particular soft drink on Facebook that comes in bottles police said were used in at least two of the attacks.

Court records show Joyner-Bell had other brushes with the law. He pleaded guilty to malicious destruction of property in Prince George’s in 2012 and was charged with failure to obey a restraining order last year, but the charge was later dismissed.

The restraining order was requested by a Bowie woman who had a relationship with Joyner-Bell and had numerous run-ins with him in recent years.

In 2011, she filed charges, alleging he broke windows in her car, according to court records. She later sought the restraining order, alleging Joyner-Bell had bitten her and shined a laser pointer in her apartment. She then filed charges, saying he violated the order by contacting her.

“The defendant seriously has mental issues that need to be addressed before someone gets hurt because of him,” the woman wrote in one of the court documents.

Ronald Banks, a neighbor of Joyner-Bell’s on Stillwater Place, said the man lived in a townhouse with his mother, his sister and his sister’s three children. Friends said he worked at a Home Depot and was interested in movies and video games.

Banks said Joyner-Bell mostly kept to himself and he regularly saw him fighting with his sister in front of their yellow townhome. One fight grew so heated that a glass door on the front of the home was shattered.

Still, he said he was perplexed by what might have set off Joyner-Bell.

“He was an average kid, but he never spoke to anybody,” Banks said of Joyner. “He would talk to your dog, but he wouldn’t talk to you.”

Pearlie Joyner, Joyner’s mother, declined to comment on her son’s case when reached by phone. “I don’t know any more information,” she said.

The blinds of their townhome were drawn tight and someone had placed duct tape over the numbers of their street address Monday. Banks said he had seen authorities remove soda bottles and a computer from the home over the weekend.

Peter Hermann, Jennifer Jenkins and Lynh Bui contributed to this report.