Annie Wilson, 73, was home alone in her third-floor apartment in south Lawrence when she smelled smoke. She opened her back door and smoke poured into the house. She ran out the front, and her parakeets flew away as she tried to rescue them.

Fire quickly consumed the building. Ms. Wilson said she lost everything, including her husband’s ashes, which were in an urn, all her family photographs and all her clothes.

“It was just crazy,” said Jessica Wilson, 43, Ms. Wilson’s daughter-in-law. “People were walking in the street with bags, kids were crying, there were sirens all over the place.”

In the long hours after the fires, sections of the communities turned dark and silent, with power turned off and people told to leave. More than 18,000 customers were without electricity at one point on Thursday night. Long lines of traffic jammed the roads out of some towns. Traffic was crammed, too, near roads to shelters that were opened to those left homeless. Some exits off the major interstate highways were closed, and officials said the area’s schools would be shuttered on Friday.

Thousands of people were left to sort out what to do. Some people said they were told to leave only if they smelled gas; others said they were told to leave regardless. Residents said they were uncertain whether to stay or go, and when they might return. “What we need folks to do is that if it’s happening in your home, you have a funny smell, just evacuate, come out to the street,” Mayor Dan Rivera of Lawrence told WBZ-TV.

The worst part, said Maria Santana, who was at home in Lawrence when she smelled gas, was that the explosions came without warning and that no one in authority seemed to have any idea of what was happening. A school not far from her home that her children and grandchildren had attended was damaged, she said.