Three people were killed and one other is believed to be trapped under rubble after a building collapsed Sunday in a poor neighborhood in this capital city, police said Sunday. The three-story building collapsed in Cairo's Sayeda Zeinab neighborhood, a police official said. Two people who were working in the building and another person who lived building died in the collapse, the official said. A woman also told authorities that she believed her son was trapped under the debris. Authorities were still searching for him late Sunday. Authorities did not know the cause of the collapse, but police were investigating.