Video from a gas station in Southwest Detroit shows a carjacker point a gun in the face of a pickup truck driver.That pickup driver is an off-duty police officer who was filling up on gas about 3 a.m. Tuesday at a BP gas station on Fort Street near Clark Avenue. Investigators said the driver went into the gas station and when he came out a gunman approached him and took his keys. The gunman then left in the victim’s truck.Police body armor and a gun were inside the vehicle, but this was not a police vehicle that was stolen.The video shows the frightening confrontation. The driver is shown dropping the keys to the truck on the pavement. The thief picks up the keys, gets in the truck and drives away.The truck was chased by officers. It crashed in Melvindale and after a short foot pursuit, officers found their suspect hiding in a backyard.The gunman was also with someone in a silver van. Police were looking for that person, too.