OK, so the robot apocalypse probably won’t happen any time soon, but the new robot sentries guarding Microsoft’s Silicon Valley campus seem like something straight out of a futuristic sci-fi movie.

According to ExtremeTech, each of the K5 security guard robots from robotics company Knightscope stands 5 feet tall and weighs 300 pounds, so you probably don’t want to mess with one.

The K5 robots don’t come with any weapons onboard—thankfully—but they use a suite of alarms, sirens, and cameras to monitor and patrol the grounds of Microsoft’s campus. If one spots trouble, it’ll either sound an alarm or dispatch a human security guard to its location.

ExtremeTech notes that the K5 can run for up to 24 hours on a single charge, and can recharge in only about 20 minutes. Its battery won’t die out in the field, though—these bots will return to the charging station by themselves when their batteries start to run dry.

The story behind the story: Robots are playing an increasingly large role in security and military operations. Google-owned robotics company Boston Dynamics, for example, has been working with DARPA to develop various robots to aid soldiers in combat settings. Meanwhile, South Korea deployed a robotic sentry to guard its side of the Demilitarized Zone in 2010. Unlike K5, though, South Korea’s guard robot came fully armed.