Updated

Authorities say the suburban Philadelphia city of Coatesville has been hit by yet another arson -- the 20th deliberately set blaze of the year.

The fire struck two homes around 1:30 a.m. Saturday. Firefighters say both houses were badly damaged.

John Hageman of the federal Bureau of Alcohol, Tobacco, Firearms and Explosives says the blaze was deliberately set.

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He declined to elaborate on how the task force determined the fire to be arson.

A 19-year-old man was held for trial Friday in connection with nine blazes between Jan. 2 and Feb. 3, including a massive fire that severely damaged 15 row homes.

Coatesville is a distressed steel town about 35 miles west of Philadelphia.