CHICAGO -- For Simon Rasin and dozens of other partygoers who were crowded on a third-floor porch, there was no warning when the floor dropped out from under them, killing 12 people and injuring at least 57. "I fell through both the second and the first floor decks into the basement area in just a pile of bodies," said Rasin, a University of Chicago law student who attended the party and whose friend, Henry Wischerath, was one of those killed. As many as 50 people, most of them in their early 20s, had crammed onto the apartment porch for a party in the city's affluent Lincoln Park neighborhood when the floor fell at about 12:30 a.m. Sunday, police said. Seven men and five women, most of them apparently on the porches directly below, were sandwiched between the falling floors and killed, said Larry Langford, spokesman for the city's Office of Emergency Management. "There was chaos," Chicago Fire Commissioner James Joyce said. "There were people screaming and crying in the alley." By Sunday evening, workers had torn the porch down. Lumber and red plastic cups littered the alley behind the building. A structural engineer conducted a preliminary examination and determined that the porch was sound, said City Building Commissioner Norma Reyes. She said the city was unable to find a construction permit for the porch, which was built in 1998. Officials found permits for other rehab work at the building that year, but Reyes said it was unclear whether the porch exceeded the scope of those documents. Langford said the Chicago Building Department was investigating to see if a building permit had been issued for any new porch work. "Thus far, there is no evidence of any criminal activity whatsoever," Police Superintendent Terry Hillard said. Partygoers who had been safe inside the apartment said they tried to rescue their friends from the pile of lumber and bodies, while people poured out of a nearby tavern to help. "They were bloodied and covered in rubble, their clothes were ripped. Women were looking for husbands, men were looking for wives. It was horrible," said Geraldine Schapira, 33, who lives nearby. Eleven people were pronounced dead at the scene, and the Cook County Medical Examiner's office confirmed that a 12th person was dead on arrival at Advocate Illinois Medical Center. The largest number of injured were taken to Illinois Masonic, which is the closest hospital to the scene. Authorities said 21 victims, in addition to the fatality, were taken there. Physicians said one victim brought to Illinois Masonic was without a pulse on arrival, but was resuscitated. She remained in critical condition. Family members identified the woman, whose name was not known when she came to the hospital, after hearing reports of the accident. Five other victims at Illinois Masonic were listed in serious condition, officials said. Sixteen people were released after being treated at the hospital, officials said. The other injured were taken to eight other hospitals: Louis A. Weiss Memorial, Northwestern Memorial, Swedish Covenant, Grant, St. Joseph, St. Francis, St. Mary and St. Elizabeth. "There were people covering me. It was pitch black and people were yelling, 'I'm dying.' I was assuming I was going to die," Natalie Brougham, 22, said. "I guess I got lucky and only had two or three people on top of me." Brougham walked away with injuries to her hip and shoulder, in pain but alive. Most of the people at the party were friends, many of them graduates of New Trier High School in Chicago's northern suburbs, Fina Cannon said. She had been in the apartment's kitchen, looking out at the porch when it gave way. "All of a sudden I saw all these heads going down," Cannon said. "The floor just dropped out from underneath them. They all went down in unison." A lot of people were on the third-floor porch at the time, and others on the second-floor porch below it, Cannon told Chicago television station CLTV. The office released the names of all the victims Sunday. They were identified as: John Jackson, 22, of Kansas City, Mo.; Katherine Sheriff, 23, of Chicago; Eileen Lupton, 22, of Lake Forest; Henry Wischerath, 24, of Buffalo, N.Y.; Shea Fitzgerald, 19, of Winnetka; Muhammed Hameeduddin, 25, of Chicago; Margaret Haynie, 25, of Evansville, Ind.; Sam Farmer, 21, of Winnetka; Eric Kumpf, 30, of Hoboken, N.J.; Robert Koranda, 23, of Naperville; and Kelly McKinnell, 26, of Barrington; and Julie Sorkin, 25, of Glenview. "It was simply a case of too many people in a small space," Joyce said. He urged people to be careful about safety, particularly with the upcoming July 4 holiday. The collapse occurred at 713 W. Wrightwood Ave., in Lincoln Park, a well-to-do neighborhood popular with young professionals just south of Wrigleyville, the area surrounding the Chicago Cubs' Wrigley Field. ------ Associated Press writers Brandon Loomis, Shia Kapos and Don Babwin contributed to this report.