GILROY (CBS SF) – Authorities in the South Bay announced Thursday that four teenage boys have been arrested in connection Ballybunion Fire that burned in Gilroy over the weekend.

According to Gilroy Police Department, an investigation determined that the cause of the fire was from the use of illegal fireworks.

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The blaze started at around 7 p.m. Sunday evening above Ballybunion Court.

A total of four male juveniles, ages 14-15 years, were seen playing with illegal fireworks described as “firecrackers” on a hillside near the 1900 block of Ballybunion Court.

As they ignited fireworks, a fire started on the hillside. Their ensuing efforts to extinguish the fire were unsuccessful and it soon spread out of control.

An area resident of the neighborhood told KPIX he saw boys running into the hills and then heard the sound of fireworks.

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“Then next thing I knew, I saw smoke over the hill and the fire started,” local resident Ed Ritters said.

Cal Fire crews established a containment line Monday and received air support to keep the fire from spreading to near-by structures.

As of Thursday, the fire had been 100 percent contained.

The four teens suspected of starting the fire were later contacted by Gilroy Police officers and interviewed. They were subsequently issued a Juvenile Contact Report (JCR) for unlawfully causing a fire. They were released into the custody of their parents. The case has been sent to the Santa Clara County Juvenile Probation Department for review and prosecution.

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While arrests were made in this case, this investigation is still open and on-going. Anyone with information regarding this investigation is encouraged to contact Arson Investigator Mitch Madruga at (408) 846-0350.