Two Pasadena teenagers faced serious charges Tuesday after being arrested in connection with throwing a homemade "bottle bomb" at a 6-year-old girl on the playground of Sunset Elementary School on Monday evening, according to Anne Arundel County police.

Police responded to the school in the 8500 block of Fort Smallwood Road in Pasadena about 6:30 p.m. for reports of an explosion, police said.

An investigation revealed two boys aged 13 and 15 had thrown a homemade plastic bottle bomb at the girl, according to police.

The device — a plastic bottle filled with household chemicals, water and a piece of aluminum foil that together cause a gaseous reaction that can force a closed bottle to explode — did explode, but the girl was not injured, police said.

Officers located the teens on bleachers at the rear of the school, where they were arrested, police said.

The teens have since both been charged, as juveniles, with felony reckless endangerment and with possession, distribution and manufacturing of a destructive device, according to police.

County police agencies throughout the Baltimore region have for years dealt with homemade bottle bombs, which teens shove in mailboxes and throw on people's lawns as pranks, they said.

"These devices are often researched online and manufactured by juveniles," Arundel police said.

But the devices aren't a laughing matter, police said.

While rarely associated with injuries, people have been hurt, police said, including an 18-year-old woman in Arundel who was taken to Maryland Shock Trauma Center in April with serious hand injuries after a bottle bomb she made exploded.

In warning the public about the dangers of the devices Tuesday, Arundel police said the devices are dangerous and that "the pressure from the explosion is capable of causing traumatic injuries to the body or extensive damage to property."

Fire investigators in the county handled a total of 28 bottle bomb cases in 2011 and six cases so far in 2012, police said.

krector@baltsun.com

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