No injuries were reported.
The fire at 1571 W. El Camino Real was reported at 7:59 a.m., April 10, according to Mountain View police spokeswoman Liz Wylie.
The entire apartment complex — about 70 apartments — was evacuated immediately following the fire, Wylie said.
Only five units were deemed uninhabitable by the city's building official as a direct result of the fire, said fire department spokesman Lynn Brown.
While most of the complex's residents were able to return home Tuesday, the fire left an entire 23-unit building with no hot water or electricity, Brown said. City staff members were ready to house 21 households in an emergency shelter at the Community Center, but most found places to stay with friends or family, Brown said. The Red Cross gave vouchers to six other households to stay in a hotel.
"The entire building is currently red-tagged," Brown said Tuesday.
On Wednesday, Brown said the cause of the fire was still undetermined.
Residents of undamaged units were allowed to gather some belongings.
The Mountain View Fire Department was assisted by fire departments from Palo Alto and Moffett Field.
Voice staff writer Daniel DeBolt contributed to this report.