PLEASANT HILL (CBS SF/BCN) — Pleasant Hill police arrested two juveniles Wednesday in connection to a grass fire near Diablo Valley College, believed to be started by illegal fireworks.

Two 16-year-olds allegedly threw a tennis ball-sized explosive mortar from a moving vehicle on Golf Club Road. The resulting fire burned a quarter-acre of grass and trees before being extinguished by firefighters.

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The device was designed to be detonated in a special launching tube, though it exploded without the tube on the ground, spraying sparks in all directions. Contra Costa County Fire Protection District officials said the fire could’ve spread to nearby homes if weather conditions were less favorable.

A witness saw the juveniles fleeing the scene near Contra Costa Boulevard and Doray Drive and called police. Officers arrested the two 16-year-old Pleasant Hill residents, who were questioned and later released into their parents’ custody.

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Fire investigators said they will refer the case to prosecutors for likely charges of unlawful fire and possession of fireworks. The suspects will likely be referred to the fire district’s youth fire setter program.

The incident follows another fire allegedly set last week in the Vine Hill neighborhood also caused by juveniles.

Fire district officials say they want to remind the public that fireworks, even those marked “safe and sane,” are dangerous and illegal in Contra Costa County. Anyone who sees people using fireworks can anonymously call the department’s arson hotline at (866) 50-ARSON (27766).

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