A Good Samaritan stopped to help a couple in a car that had crashed in the Oakland hills early Saturday, but things turned bad fast in a flurry of fists and blood, with one man in jail before the morning was over, police said.

The would-be helper was driving on Skyline Boulevard around 1:30 a.m. when he saw a BMW sedan smashed against a tree and the driver flagging him down for help, authorities said. When the Samaritan pulled over to help, the other driver allegedly pulled a shotgun and tried to rob him of his belongings and his car.