Bloomingdale's in New York City turned aways thousands of customers Saturday morning because of a fire which broke out before the store opened for business. It was the second fire at the store in six months.

The blaze, considered to be of electrical origin, started in a third floor area under renovation and wiped out a neighboring sweater and blouse department, as well as Paradox, the avant-garde clothing area.Water used to control the fire also damaged seriously a large section of junior sport-swears on the floor below. All departments were newly stocked with fresh fall merchandise.

Marvin Traube, Bloomingdale's president, said it was not possible to estimate the dollar damage, but he expected the loss of business to be made up.

"We never lost business from last month's blackout," Traube said. Bloomingdale's had attempted to open their store during New York's recent blackout but by early afternoon conceded it wasn't possible and sent the sales help home.

The store in fact did open for business at 2:30 Saturday. The heavily damaged areas were cut off from customers by white cotton and vinyl sheeting, but the smell of was still strong on the first three floors.