The lower portion of Flight 2176's wingtip hit a bus near the gate area, the spokesperson said.
No one was injured, and the aircraft sustained minor damage, the spokesperson said.
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The plane returned to the gate, and passengers were able to get off normally.
"We apologize for any inconvenience and will accommodate our Las Vegas-bound Customers on another aircraft," Southwest said in a statement. "Nothing is more important to Southwest than the Safety of our Customers and Employees."
The airline is working with local authorities to investigate.