More than 300 iPhone X devices were stolen from a delivery truck shortly before Apple's newest smartphone went on sale Friday.

The thieves stole the phones after breaking into a UPS truck while its driver was making a delivery at the Stonestown Galleria shopping mall in San Francisco.

Considering the iPhone X's price of between $999 and $1,150 in the U.S., the total value of the stolen devices was estimated to be more than $370,000.

Three suspects, who allegedly drove a white Dodge van, remain at large, media reports said.

The iPhone X was launched for sale on Friday in more than 50 markets, including the U.S., China and the U.K.

Long, snaking lines formed outside Apple stores in Asia and Australia early on Friday as fans flocked to buy the new iPhone X, a turnout that contrasts with the more lackluster launches for the past two iterations of the premium smartphone.

Strong initial demand underscores Apple's upbeat sales forecast for the year-end holiday shopping season, provided just hours before iPhone X sales began.

The iPhone X is a special 10th anniversary model, a glass-and-stainless-steel device that Chief Executive Officer Tim Cook billed as "the biggest leap forward since the original iPhone."