Thieves stole nearly $1 million worth of trading cards from a FedEx truck in Orange County, California, in a heist last week that highlights how collectibles have become a new target for robberies.

Hundreds of sports and Pokémon cards valued at around $963,000 were taken from the FedEx truck in Santa Ana, California, local police said. The truck was transporting the trading cards from a firm that helps owners value their collections and was due to ship them back.

“This is by far the most valuable shipment of cards I would’ve ever had,” said Skyler Bennett, a card trader who goes by “SKY-B CARDS” online.

Bennett said in a video on YouTube that 104 of his trading cards, which he had insured for $156,000, were stolen. In July, he had dropped off the cards at a company called Professional Sports Authenticator and paid it $8,000 to authenticate and grade them.

After completing the process, the firm was shipping the cards back to Bennett in Michigan. Santa Ana police said two pallets of trading cards were taken from the FedEx truck, while a third pallet showed signs of having been disturbed. The lock on the truck was also taken, police said.

FedEx said: “The security of our customers’ shipments is top priority, and we are working with local law enforcement in their investigation.”

Once a children’s hobby, trading cards have become a lucrative investment. Rare cards can be worth as much as $16 million. Live shopping streams online buzz with people buying up unopened packs in search of a prized card that can make them wealthy.

Key to the burgeoning market are firms such as Professional Sports Authenticator, based in Santa Ana, which authenticates and appraises cards.

PSA said the items were not in its possession at the time of the burglary and that it had learnt of the theft from the shipping carrier.

The firm said it had deactivated the certificates of the stolen items and notified marketplace partners so they could look out for rare and serialised items. It said it was also taking steps to compensate owners for the fair market value of their stolen cards.

“We understand the impact this has on collectors involved, many of whom see these cards as far more than a financial asset,” PSA said.

Burglars have targeted trading card shops in Chicago and New York this year. In January, three armed robbers smashed display cases at a Pokémon card shop in New York City’s Meatpacking District and grabbed merchandise, the store’s owner said on Instagram.

The thieves also pointed guns at customers who were at the store for a community arts-and-crafts event to decorate covers for their favourite cards. The store’s owner said all the customers and employees were unharmed.