Many stores looked empty this Black Friday.

However, if retailers can pull off online success, there's no need to panic over a lack of crowds.

Online sales from Black Friday and Thanksgiving reached $6.3 billion on Friday evening.

Many stores were empty this Black Friday — but retailers have no need to panic.

Some shoppers were surprised to find empty Targets, Best Buys, and Walmarts when they showed up for Black Friday shopping.

When Business Insider's Sarah Jacobs arrived at the Atlantic Terminal Mall in Brooklyn early Friday morning, she found a meager line outside waiting for the mall to open, and even fewer people outside Target and Best Buy.

Empty malls seem like bad news for retailers. However, with the growth of e-commerce and services like in-store pickup, retailers can cut down on store traffic while still growing sales.

Shoppers spent a total of $3.54 billion online as of 8 p.m. ET on Black Friday, a 15.6% increase over last year according to Adobe Analytics. That's on top of the $2.87 billion spent on Thanksgiving Day.

Shoppers are expected to spend $107.4 billion online this holiday season, which would represent an increase of nearly 14% over last year, according to Adobe.

Another reason that stores are emptier is due to Black Friday sales being spread out almost a whole week instead of centered on a single day. Cyber Monday is anticipated to generate more money than Black Friday. Thanksgiving Day is also increasingly important, growing sales by almost 15% from 2016 to 2017, according to data collected by tax automation software provider Avalara.

Ultimately, when customers are in stores, that's not always a good thing. On Friday, Macy's had plenty of lines — but it was because the retailer's credit card system was down at many locations, and customers were struggling to check out and pay for their purchases.