LYNN – A Lynn man was nabbed for an armed street robbery seconds after it occurred outside 21 Bloomfield St. on Monday, police said.James Legault, 20, who provided a last known address of 280 Chestnut St., was arrested and charged with armed robbery shortly after 1 p.m.Police say a 27-year-old man was chatting on his cell phone and walking up his front stairs when Legault approached him without warning.Legault allegedly pulled out a box cutter and demanded the man’s cell phone.The victim handed over his phone. At the same moment, a police car just happened to be driving down the street.The victim waved down Officer Michael O’Connell, who quickly placed Legault under arrest.