FedEx Corp. on Tuesday suspended its domestic express freight services due to a staff shortage as cases of the Omicron variant of the coronavirus rose.

The delivery firm said it is suspending the economy domestic FedEx express freight, including FedEx two-day freight and FedEx three-day freight services.

International economy freight pick-up services, which had been paused earlier, resumed on Monday, FedEx added.

Last month, the company had warned that rising cases of the Omicron variant had caused a staff shortage and delay in shipments transported on aircraft.

Severe winter storms around the country and staff shortages had forced several U.S. airlines to cancel flights last month. U.S. coronavirus deaths rose by at least 2,266 on Monday to a total of 890,049 compared to 887,783 previous day, according to a Reuters tally.