Home resales in September clocked the largest monthly increase in 26 years as buyers scrambled to complete their purchases before a tax credit for first-time owners expires.

Sales jumped 9.4 percent to a seasonally adjusted annual rate of 5.57 million last month, from a downwardly revised pace of 5.1 million in August, the National Association of Realtors said Friday.

That pace was the strongest in two years and beat Wall Street forecasts. Sales had been expected to rise to an annual rate of 5.35 million, according to economists surveyed by Thomson Reuters.

"There's a mini-boom going on in the housing market," said Thomas Popik, who conducts a monthly survey of real estate agents for Campbell Communications, a research firm.

Nationwide sales are up nearly 24 percent from their bottom in January, but are still down 23 percent from four years ago.

Prices, however, continued to be dragged down by foreclosures and short sales, where the mortgage exceeds the sales price. The median price last month was $174,900, down almost 9 percent from $191,200 a year earlier, and slightly lower than August's median of $177,300.

The inventory of unsold homes on the market fell about 7 percent to 3.63 million. That's less than an eight-month supply at the current sales pace, and the lowest level since March 2007.

Sales rose around the country, especially in the West, where they grew 13 percent from a month earlier. Foreclosure sales are booming in cities like Los Angeles, San Diego and Las Vegas.

First-time homebuyers and investors are snapping up those homes and taking advantage of low mortgage rates. These buyers can also take advantage of a tax credit of 10 percent of the sales price, up to $8,000, if the sale is completed by the end of November.

The concern is what will happen after November. Many buyers are very aware of how soon they need to close and seem to be pushing to make sure they get every penny.