Hours before the fleet was grounded, officials confirmed that the death toll had risen to 14 after another body was found, with buildings caught up in the fire still being searched for more victims.
"We pray for each of the victims' families and pray that no additional victims are lost," Louisville Mayor Craig Greenberg said.
In a statement, UPS said the decision to ground 9% of its fleet was out of an "abundance of caution".
It is unclear to what extent delivery services will be impacted by the moves from UPS and Fedex.
UPS said contingency plans were in place to continue service. A statement continued: "Nothing is more important to us than the safety of our employees and the communities we serve."
The model of aircraft involved in the crash was a MD-11F triple-engine plane, which first entered service 34 years ago with Thai Airways as a passenger jet, but was transferred to UPS in 2006.
MD-11s were originally manufactured by McDonnell Douglas, before the company merged with Boeing in 1997.
According to the National Transportation and Safety Board, the left engine caught fire and detached from the wing during take off.
The aircraft was carrying 38,000 gallons (144,000 litres) of fuel as it attempted to disembark for a long flight to Hawaii, which contributed to the size of the fire which broke out after the crash.