Fast-growing Amazon.com has leased most of another downtown Seattle office tower, the 28-story West 8th building in the Denny Triangle, city permit records indicate.

Fast-growing Amazon.com is leasing most of another downtown Seattle office tower, the 28-story West 8th building in the Denny Triangle, city permit records indicate.

Applications were filed Tuesday with the Department of Planning and Development for building permits for alterations to “Amazon floors” seven through 10 and 15 through 24 of West 8th.

Those 14 floors total about 280,000 square feet — most of the vacant office space remaining in the 500,000-square-foot building, according to commercial real-estate database Officespace.com.

An Amazon representative declined to comment, as did A-P Hurd, vice president of Seattle developer Touchstone, which built West 8th with Prudential Real Estate Investors.

West 8th, on the block bounded by Eighth Avenue, Westlake Avenue and Virginia Street, was finished in mid-2009. It has remained mostly vacant while many other downtown office projects completed around the same time leased up.

The building’s tenants include Casey Family Programs, Seattle Children’s Research Institute and Salesforce.com.

Amazon already occupies or has leased more than 2.3 million square feet of office space on downtown’s northern edge, most of that at its new headquarters complex in South Lake Union.

Earlier this year, the online retailer leased 460,000 square feet at 1918 Eighth, another newer tower kitty-corner from West 8th.

There’s talk the company may be in the market for even more space. Touchstone and Vulcan Real Estate, which developed Amazon’s South Lake Union complex, recently filed preliminary paperwork for proposed office buildings in that neighborhood totaling nearly 1 million square feet.

The developers haven’t said whether their applications were motivated by Amazon.

Amazon, which does not disclose the size of its local workforce, employs 51,300 people worldwide, up from 31,200 a year ago. What’s more, the company appears to be on a hiring spree. Its website lists more than 2,000 job openings in Seattle.

Last month, Amazon said its third-quarter sales rose 44 percent to nearly $11 billion, but its profit fell 73 percent to $63 million amid increased costs.

Seattle Times business reporter Amy Martinez contributed to this report.

Eric Pryne: 206-464-2231 or epryne@seattletimes.com