Recent assaults against transit security officers at San Diego trolley stations have some asking whether the officers are adequately trained, 10News reported.From a distance, some of the officers look like police officers. However, a closer look at a uniform patch says otherwise -- it reads Transit Systems Private Security."Their primary job is to ensure the safety of the passengers," said Rob Schupp, director of communications for the Metropolitan Transit System.In the past couple of weeks it has been transit security officers who have been attacked.Video footage taken at the Grossmont trolley center on July 18 captured the moments after police said a security guard was shot twice and had his gun stolen.Two days before, another officer was attacked and his gun was stolen at a station in Encanto.Police arrested Marquise Loftis in connection with the trolley station attacks.Last Sunday evening, a transit security officer was attacked by a drunken man who attempted to grab the officer's gun at a trolley station in the Mountain View area."These things are very rare," said Schupp.Schupp said the three recent cases are isolated incidents, but many are concerned over whether the security officers are adequately trained.The officers are hired through a private firm called Heritage Security Services."They are a very professional organization. They do extensive training with all their employees," said Schupp.State regulations require that all security guards have a minimum of 40 hours of training, but this does not include weapons training.10News talked to Ken Muller, president of Heritage Security Services, who said the transit security officers receive 164 hours of training, and those carrying weapons must be re-qualified every quarter."Do you feel it's safe?" asked 10News' Evy Ramos."I think it's very safe. Heritage knows what they're doing. They have a certified tactic specialist on their team, and so every week they retrain people and teach them the latest techniques," said Schupp.For the time being, officials said extra transit officers will patrol local trolley stations.