Electrical wiring caused the blaze that killed a family of four early Monday in West Philadelphia, fire officials said Wednesday.

The blaze, which broke out just before 5 a.m. in a rowhouse on Chancellor Street near 52d Street, killed Rishya Jenkins, 23, her stepson Cyncere McClendon, 4, her son Jayden McClendon, 2, and Seneca "Chuck" McClendon, 75. It was the city's third fatal fire in a week. Jenkins was planning to get married in June; her fiance discovered the fire and tried vainly to save his family. The elder McClendon, a retired postal worker, had lived on the block since the early 1980s.

"Non-permanent electrical wiring" was the official cause. That means wiring such as extension cords, Executive Chief Richard Davison said.

A fire on Sunday that killed a 4-year-old girl and her great-grandmother in North Philadelphia was caused by unattended cooking, fire officials ruled. That fire, in a rowhouse on Firth Street near 13th, left Nevaeh Bryant, 4, and Ardalia Bumpus, 79, dead. - Dana DiFilippo