LYNN – An 18-year-old Lynn man was quickly arrested Sunday after he allegedly robbed three brothers at gunpoint as they walked down Chatham Street.Jonathan Monserrate, 18, of 199 Chatham St., was arrested and charged with three counts of armed robbery while masked, three counts of assault with a dangerous weapon and assault and battery with a dangerous weapon (shod foot) shortly after the 2:30 a.m. robbery.Judge James Lamothe ordered Monserrate held on $10,000 cash bail at his arraignment Tuesday in Lynn District Court.The brothers, ages 18 to 20, said they had just left 7-Eleven on Essex Street and were walking down Chatham Street when suddenly a man held a gun to the back of one of the victims and demanded money.Monserrate allegedly ordered all three men to lie on the sidewalk and took one of the victim’s wallets, iPods and a small amount of cash. The victim’s wallet, containing his driver’s license, was found in Monserrate’s possession when police stopped him walking on Marianna Street a few minutes later, police said.The suspect was positively identified by all three victims as the person who robbed them.One of the victims was allegedly kicked in the stomach as he lay on the ground before the suspect fled.Police found a black BB gun ditched in a snowbank a short distance away from where Monserrate was apprehended, police said.Monserrate was ordered back to court Feb. 17 for a probable cause hearing.