WEST VALLEY CITY, Utah - The flames are out, the fire crews are gone and now investigators are trying to determine what sparked the blaze.
Authorities said several West Valley police officers first spotted the flames and may have saved some lives.
The first call came in just before 3 a.m. Friday.
Fire crews put out the flames in about 30 minutes and credit police officers on routine patrol for initially containing the fire.
Three of the four officers suffered minor smoke inhalation but are expected to be just fine.
Police said the same officers were called out to the same complex earlier that night when gun shots were reported.