VIDEO: The cause of a fire that reached nine alarms in Dorchester on Saturday remains under investigation. One resident, Maria Nguyen, filmed the fire with her cellphone for six seconds, but then stopped recording to call for help. "I ran in to try to grab my daughter. I called 911. And then as soon as I ran back out from the house, the fire just started spreading to the next house," Nguyen said. She watched as flames ripped through the vacant house at 39 Old Morton Street near the Dorchester/Mattapan line Saturday night. "This whole area had this pitch black cloud go by. It was very scary," she said. The vacant building caught fire and spread to eight surrounding structures before it was contained hours later by over 100 firefighters — seven of whom were transported to local hospitals due to injuries sustained battling the blaze. High winds and the close proximity of the homes are among the factors being blamed for the quick spread of the fire that affected nearly 20 families in the neighborhood.