The outside walls are going up at the Amazon distribution facility under construction in Chattanooga as the massive center begins to take shape.

The developer of the center, which at 1 million square feet is nearly the size of Hamilton Place mall, says it's on a fast track to meet the aggressive deadline Amazon has set. The online retailer is aiming to begin handling and shipping thousands of items to customers before Christmas.

"The deadline is fast approaching," said Charles Wells, a vice president for Seefried Properties of Atlanta.

He said plans are to turn over the center's keys to Amazon by Oct. 1.

Amazon plans to hire more than 1,400 full-time workers and more than 2,000 part-timers at the Enterprise South industrial park site and another center in nearby Bradley County.

Wells said Seefried also is overseeing development of Amazon's Bradley location. Amazon is investing about $139 million in the two Southeast Tennessee sites.

He said the two centers are Amazon's first-ever build-to-suit distribution facilities among its array in the United States.

Wells expects the construction work force to peak at between 400 and 500 people at the Chattanooga site.

"That will only last for months," he said. "We've got to get a lot of work in place quickly. It's full speed ahead."

Amazon can hardly see its distribution, or fulfillment, centers go up fast enough, Wells said.

Goldman Sachs, a Wall Street investment bank, said in a research note earlier this year that Amazon will add more than 7 million square feet of distribution space this year, up 40 percent. The additions will bring Amazon's total to 24.3 million square feet at home and abroad.

J.Ed. Marston, the Chattanooga Area Chamber of Commerce's vice president of marketing, said the project is on schedule.

"That bodes well for employing Chattanoogans and Hamilton County residents as soon as possible," Marston said.

Amazon has said it plans to hold job fairs this summer.

The 79.1-acre site of Amazon's Chattanooga distribution center is owned by the city Industrial Development Board and leased to an Amazon affiliate. The city and county granted property tax breaks on the property near the new Volkswagen plant for the next decade to help entice Amazon to locate in Chattanooga.