In Morrisville, a zap and then: "Our roof is on fire."

Donna Hughes and her boyfriend, Jim Maguire, had grown used to the electrical problems in their building.

They'd been renting the two-bedroom apartment on the second floor of a brick rowhouse in the working-class borough of Morrisville, Bucks County, for the last five years. It was well-maintained by the landlord, Hughes said. "But these are really old houses. The circuit breaker would trip, the lights would go out, and we'd reset it."

About 10 p.m. Saturday, Maguire went to the bathroom, flipped the light switch, and heard a zap.

"The light's out again," Hughes heard Maguire say, then, "I think our roof is on fire."

"Are you kidding me?" she said, thinking he was joking. But then she got up to see for herself. "In a second, a split second, flames were shooting from the ceiling."

Hughes, a 37-year-old disabled lab technician, screamed, "Oh my God! Our roof is on fire!" She called 911.

"I could barely talk," she said Sunday. "Help," I said. "Please. Fire. I couldn't get the words out. The fire spread so fast, I thought everyone was going to die."

Hughes ran around the apartment, scooped up her purse, her Chihuahua, and her cat, grabbed her 11-year-old daughter's hand, and ran.

On the way down the stairs, she yelled to her neighbors, "Everybody get out!"

Everything after that, she said, was a blur. She heard snapping noises and worried that something was going to explode as she blindly pulled her daughter through a choking cloud of smoke. For a moment, she lost her bearings but kept running until the cold night air hit them with blunt force.

In all, the four-alarm fire destroyed 10 rowhouses and left seven others uninhabitable - sodden and acrid with smoke. It took an estimated 75 firefighters more than an hour and a half to bring the blaze under control, Morrisville Fire Chief Matt Wiedenhaefer said.

"Fortunately, there were no injuries," he said.

Anthony Vandeven, lead responder for the local Red Cross, arrived around 1 a.m. to find what he described as one of the biggest fires he'd seen. He recalled watching "a river of water" flowing along Philadelphia Avenue.

Hughes had been wearing shoes, but her daughter and Maguire were barefoot and none of them had had time to throw on coats. A few neighbors, noticing the three of them huddled and shivering, went back into their apartments and returned with coats, blankets, and shoes.

"It was pretty amazing, the help," Hughes said. "People we didn't even know gave us anything they could."

Steven Hopkins, 56, who runs a salvage business, was logged on to Craigslist, posting some antiques for sale, when he sensed something was amiss. Hopkins, who lives a half-dozen houses down from Hughes, opened his back door and smelled smoke. He alerted his roommates, one of whom is a frail 82-year-old man who was sound asleep, helped them gather up a few belongings, and then hustled outside.

"We were lucky," Hopkins said. "They were able to stop the fire before it hit our house. But we're still homeless because they won't let us back in until they check everything to make sure it's safe."

Morrisville's fire marshal ruled Sunday that the fire was caused by an electrical malfunction in a bathroom ventilation fan - as Hughes described.

The Red Cross helped 10 families - a total of 34 people and numerous pets - find shelter, said Dave Schrader, spokesman for the Southeastern Pennsylvania chapter.

The number of people seeking shelter will likely increase, given the number of homes damaged, Schrader said.

Speaking from a nearby Comfort Inn where the Red Cross had provided a room for her and her family, Hughes said she was trying to hold herself together, with little success, and that her daughter had been inconsolable.

"They put us up in here for the next few days, but - after that, we're pretty much homeless," she said. "Every time I close my eyes, I see flames and smoke and lights. I've never experienced anything so awful in my entire life. I know it happened, but it seems like a movie."

Maguire, 33, was just laid off from his job at OfficeMax this month, she said. And her landlord, who she said stayed with her the entire time until she was taken to the hotel, has told her the building "is not salvageable."

On Sunday morning, firefighters were still walking across roofs and climbing in and out of second-story windows, looking for hot spots under the eaves.

"We lost everything," Hughes said. "Furniture, clothes, computers, TV." Fire officials briefly allowed her back in the apartment to fetch a few belongings.

"It looks like a war zone. There are no walls. No roof."

But she did find a few essentials intact. The urn containing her father's ashes. Her daughter's medicines. And a photograph of her family.

"It was in a heart frame sitting on my bedroom nightstand," she said. "It was the only thing in there that didn't burn for some odd reason."