U.S. home prices soared the most in 15 years, with low mortgage rates and a scant inventory of properties to buy fueling a tight housing market.

Nationally, the S&P CoreLogic Case-Shiller index of property values climbed 12% in February from a year earlier, the biggest jump since 2006. That followed an 11.2% gain in January.

Home prices in 20 U.S. cities jumped 11.9%, meanwhile, beating the median estimate of 11.8% in a Bloomberg survey of economists.

"Homes in many areas went under contract in January — generally one of the slower times of the year — merely days after hitting the market and about a month faster than the same period a year ago. Seeing this, and unfazed by rising mortgage rates, a wave of eager buyers is being forced to act swiftly and face heightened competition for the few homes available," said Zillow Economist Matthew Speakman in a released statement about the report. "The combined dynamic is pushing prices upward at their strongest pace in years, and it doesn’t appear that there is an end in sight."

Historically low mortgage rates have been at the center of the pandemic housing rally, increasing buying power as Americans look to upgrade their properties. With inventory tight, prices have jumped to record highs.

Phoenix, San Diego and Seattle reported the biggest year-over-year gains among the 20 cities in February.