Pattern on National Mall grass appears to show '8647,' numbers associated with threats to Trump

Someone created a pattern on the National Mall grass that appears to show "8647." 

The numbers have been used by opponents, and the Trump administration has said they are meant to convey threats to the president. 

The numbers are formed by a pattern of brown spots contrasting with the greener grass around the spots. U.S. Park Police said in a statement that the cause of the discoloration isn't known, and samples have been collected for testing as part of its investigation, 4 Washington reported. 

"The deranged vandalism on our National Mall will not be tolerated. Any threat against the President is taken very seriously by the Department, and our U.S. Park Police will investigate this incident and hold those responsible accountable," Park Police said. 

The number 86 has been used to refer to removing someone, and Trump is the 47th U.S. president. Former FBI Director James Comey was indicted on charges of making threats against Trump after he posted a photo on Instagram showing seashells on a beach arranged to show the number 8647.