Authorities say four adults and three children have died in a fast-moving Massachusetts apartment fire, and nine others have been hospitalized with non-life-threatening injuries.
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Middlesex District Attorney Marian Ryan is pledging to conduct a "long and thorough review" into Thursday morning's fire in Lowell that had tenants jump or hand children to safety.
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She says it will be a "fairly long time" before the victims are identified.
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The investigation will include whether the alarm system was working and whether there were fireworks in the building, as some witnesses described hearing explosions.
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Ryan says investigators have already contacted building ownership. (AP)Â
