An early morning fire of suspicious origin burned through four houses in Troy, N.Y., leaving about 23 people homeless, fire officials said. No injuries were reported. The blaze early Sunday appeared to have started in a vacant structure that was set afire, apparently intentionally, in late July, the Albany Times Union reported. A few hours before the latest fire, firefighters had put out a small fire at a house on the same block. Officials said that fire was fully extinguished and did not cause the later fire. Seven families lived in the four houses. In one of them, a single mother with five children, ages 1 to 11, lived on the first floor and her parents lived on the second floor. Fire officials said there have been a number of suspicious fires in the city, near the state capital of Albany, since mid-July.