DETROIT -

Several Detroit Public Schools released students early Friday due to loss of heat in the buildings.

The school district says there is no heat in the buildings because there is a power outage in the Detroit Public Lighting system.

High schools were dismissed immediately. Students at all other schools were dismissed after their parents or guardians were notified. Students riding busses were not released until a parent or guardian was contacted.

Mayor Mike Duggan's office says the outage was caused when a cable feeding a major substation failed about 10:45 a.m. Friday.

Spokesman John Roach says it caused extensive outages on Detroit's west side. Roach also says the condition of the electrical system and cables being used beyond their normal lifespans contributed to the power failure.

All power was expected to be restored by the end of Friday.

According to DPS, the school district has experienced more than 117 Detroit Public Lighting outages since Jan. 1, 2014. About 6,000 students were impacted by Friday's outages.

Here are the schools included:

Ann Arbor Trail
Bagley
Bates
Bow
Breithaupt
C. Wright
C. Young
Carver
Cody
Cooke
Dixon
Dossin
Edison
Emerson
FLICS
Gardner
Greenfield Union
Henderson
Jerry L White
JR King
Ludington
Mann
Palmer Park Academy
Pasteur
Randolph
Renaissance
Schultz
Vernor
West Side Academy
West Side Adult