An eight alarm blaze completely destroyed a five-story brick apartment building and severely damaged a second in Central Square late Friday night, leaving 100 people homeless, but miraculously no one was seriously injured.

One hundred forty firefighters from across the state and dozens of police and emergency disaster personnel responded to the fire, which raged from 11 at night to well into Saturday morning. Thick, black smoke billowed from the buildings for hours and brought the Central Square area of Cambridge to a grinding halt:

. Twenty-nine families who lived in the three buildings were driven into the street.

. More than 12 blocks of streets along Mass. Ave. were roped off by police and fire personnel Friday night and throughout the entire day Saturday. Pedestrian and motor vehicle traffic in the area was completely halted.

. Public bus service in the area was stopped, and buses were still being rerouted late yesterday afternoon.

An eight alarm fire raged through CentralSquare Friday night, destroying one building andbadly damaging another. Twenty-nine families wereput out on the street. Public transporation waseither re-routed or shut down. Thick, black smokelimited visibility to less than 50 feet.Miraculously, no one was injured, but as oneCambridge police detective on the sceneobserved,

. The MBTA subway station at Central Square wasclosed until late Saturday afternoon. MBTAofficials, who were directing passengers tosubstitute shuttle busses Saturday, said theyworried the burning buildings might collapse andcrush the subway below.

. One of the two buildings was demolishedSaturday with a wrecking ball and other heavyequipment.

. A McDonald's restaurant and an unfinishedfurniture store located on the ground-floor of thebuildings sustained substantial smoke and waterdamage in the blaze.

`It was so bad you couldn't see 50 feetin front of you," said Cambridge police Det. FrankPasquarello, who assisted in the emergencyresponse late Friday night and early Saturdaymorning. "It was a nightmare."

Authorities said the cause of the blaze isstill under investigation, but does not appear tobe suspicious. Deputy Fire Chief John J. Gelinassaid yesterday there was nothing to indicate arsonas a cause of the fire. It appears that the blazewas accidental, Gelinas said.

Pasquarello said potentially hazardouschemicals, such as paints or varnishes, stored inthe unfinished furniture store on the first floorof one of the buildings, might slow theinvestigation.

Firefighters working at the scene said theywere awed by the extent of the damage. Gelinassaid fire alarms were in place and sounding in theburned buildings.

American Red Cross disaster service workersarrived at the fire around midnight and began a'round-the-clock operation to provide emergencyservices for the families who lost their homes.Most of the residents were low-income Haitian andHispanic families.

For now, the displaced families are staying atCambridge Rindge and Latin High School, afterspending Friday night at the smaller St. Paul'sAfrican Methodist Church.

Authorities said the fire was broughtunder control around 2 a.m. Saturday morning. Buteven late Saturday afternoon, firefighterscontinued to pump thousands of gallons of wateronto smoldering embers.