A man robbed a bank Tuesday morning in Littleton, then fled across the street and tried to hide — in another bank, ­police said.

Christopher Grannis, 25, of Littleton, was arrested just before noon Tuesday and charged with bank robbery, assault, and intimidating a witness, said Deputy Police Chief Matthew J. King. He said Grannis passed a note to a teller, who then handed him an undetermined amount of cash at the Northern Bank and Trust at 11:20 a.m.