WEST -- After the explosion at West Fertilizer Co. interrupted a quiet evening, Mandy Williams ran from her home, bewildered."I thought we were under attack," said Williams, 27. "I thought 9-11 had come here."Two blocks from her home, she found houses on fire and others with far more serious structural damage than her own.Williams and some other residents were allowed at least a brief visit to their homes Saturday. But those living closer to the blast zone have a longer wait, and she said many will be in shock when they see the damage."I really worry about them and then this town when everybody sees it," she said. "It's so much worse than what is on this block. It's nothing compared to what's over there. A lot of those homes are gone."Those who were allowed into their homes, three days after the fatal explosion, were urged just to grab a few possessions and see if the structures were still sound.The restricted area, which is about a mile from the blast site, was under a curfew from 7 p.m. to 7 a.m., and residents were not allowed to wander around.Also Saturday, investigators said they still don't know where the fire started or what caused the explosion, which came some 25 minutes later as firefighters tried to extinguish the blaze Wednesday.Fourteen people, most of them firefighters, were killed when the plant exploded. Two hundred people were injured in the blast, which blew apart a 15-unit apartment complex across the railroad tracks and damaged a nursing home and school.Investigators with the state fire marshal's office and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives had finished examining the area that was opened to residents Saturday. Workers were scheduled to remove one of the destroyed tanks Saturday night, and Union Pacific was scheduled today to begin repairing the tracks that run past the plant.Officials declined to discuss the amount of chemicals stored at the plant, which distributed fertilizer to farmers. A report by the Reuters news agency said the plant had been storing 1,350 times the amount of ammonium nitrate that would have triggered oversight by the Department of Homeland Security. A source told the news agency that the amount had not been disclosed.Some 50 homes were destroyed, said Sgt. Jason Reyes, a spokesman for the Texas Department of Public Safety.Drivers lined up for blocks in the south part of the city Saturday, awaiting permission to enter the restricted area.Tom Juntunen, a construction worker who lives about eight blocks from the plant, was one of the first in line. He had seen his 1970s brick home long enough early Thursday to know that it has significant damage."The garage door looks like somebody drove into it," he said. "The front door looks like it has been kicked in by the SWAT team, but the inside of the house looks OK."Juntunen, 33, said the destruction he saw in his neighborhood proves that homes closer to the blast site will require a major rebuilding project."It's far worse than what you've seen on TV," he said. "The pictures out there don't do it justice. Some areas will have to be completely rebuilt."With boil-water notices in effect for his neighborhood and limited natural gas or electricity, Juntunen said, he wouldn't be sticking around.During a town hall meeting Saturday, Mayor Tommy Muska apologized for failing to communicate with residents, telling them he was focused on technical aspects of the situation.He said the damage northwest of the site is the worst. "When you see this place, you will know a miracle happened," he said.He was reluctant to give a timeline on when residents in that area could get to their homes. He said the re-entries will be divided into three stages and hoped everyone would get in within a week.Bill and Melissa Warren, who live farther from the plant, were among those waiting to return Saturday.Melissa Warren was several blocks away from West Fertilizer shortly before 8 p.m., when the explosion rocked her Dodge pickup, cracking the windows and setting off the airbags.She and her husband, Bill, made it back home, only to be told to leave 30 minutes later."I was getting the kids to take a bath, getting the pots and dishes together that had fallen on the floor, and trying to act like everything was normal," she said.Her husband said he had seen no obvious signs of structural damage, but he planned to look closer once he got inside."I'm planning on climbing up in the attic and seeing what I can find," he said. "I think we're OK, but we really don't know."Warren left the West volunteer fire department about nine years ago because his job prevented him from making the meetings.But he still knew most of the firefighters who lost their lives. Five of the 29 West firefighters died, and five more were hospitalized after the blast."This is a tightknit place where everybody knows everybody's business," he said. "I was close to a lot of them. It's a real loss for the community. They were just doing their jobs."Later Saturday, after Bill Warren returned from the visit to his 1910 home, he had bad news.Some of the main rafters in his attic were split."I told my wife when we pulled up the roof doesn't look right," he said.He plans to talk with his insurance company today."It's livable," he said. "We could be there tonight. But there's no running water and no one under 18 is allowed in, so my kids can't stay there."I'm not going to speculate on how serious it is. I'm not an expert."This report includes material from The Associated Press.